Onigiri Fillings
The best onigiri fillings balance flavor, texture, and moisture. A little salty salmon, tangy umeboshi, savory kombu, or creamy tuna mayo can turn warm rice into a satisfying snack or lunch. The key is keeping the filling compact and not too wet, so it stays in the center while the rice holds its shape.
For one medium onigiri, start with about 1 to 2 teaspoons of filling. Choose a flavorful center that is cool, finely chopped or flaked, and drained of excess liquid. Wrap it with warm, sticky short-grain rice, then add nori just before eating if you want it crisp.
There is no single required filling. Japanese rice balls can be stuffed in the middle, mixed through the rice, wrapped around the outside, or simply seasoned. Familiar choices include salted salmon, pickled plum, bonito flakes with soy sauce, seasoned kelp, and tuna mayonnaise. Home cooks also use vegetables, cooked meats, eggs, and whatever small leftovers make a good bite.
This guide walks through the classic fillings, easy vegetarian ideas, quick recipes, flavor pairings, and shaping tips. For another recipe-led overview, see Just One Cookbook’s onigiri recipe with four filling ideas. If you are new to rice balls, start with our complete step-by-step guide to making onigiri; it covers rice, shaping, and wrapping. Then come back here to pick a center that suits your taste.
How much filling should go inside?
A good starting amount is 1 to 2 teaspoons for a medium rice ball, or roughly 10 to 15 grams depending on how dense the ingredient is. Use less for strongly salted umeboshi, concentrated miso, or spicy roe; use a little more for mild flakes or chopped vegetables. The goal is a noticeable center without making the rice shell so thin that it splits.
Think of the filling as a small core, not a layer spread edge to edge. Place it in the middle of a shallow cup of rice, cover it completely, and close any gaps. If you can see the filling through the rice, add a little more rice to seal it. A dry exterior makes shaping easier, while a center with too much oil, sauce, or water can leak through and loosen the rice.
Choose a concentrated filling, use a modest spoonful, and keep it fully enclosed. You can always add more filling to the next rice ball once you know how your rice and hands handle it.
Classic Japanese onigiri fillings
These well-known combinations are useful starting points because their flavors are bold enough to stand up to plain rice. The exact seasoning varies between households, regions, and packaged versions, so taste as you go and adjust the saltiness to your preference.
1. Salted salmon (shake)
Cooked salmon flakes are savory, tender, and easy to portion. Roast, pan-cook, or grill a small salmon fillet with a light sprinkle of salt, then cool it and flake it finely, removing any bones and skin. For six medium rice balls, about ½ cup of flaked salmon is usually enough. If the fish is moist or oily, blot it lightly before using.
For a quick variation, mix the flakes with a pinch of toasted sesame or finely chopped shiso. Keep the add-ins subtle so the salmon stays the main flavor. Salmon can also be mixed through the rice, but a central pocket gives a classic contrast between plain rice and savory fish. The Japanese Ministry of Agriculture, Forestry and Fisheries features salmon among familiar onigiri ingredients in its onigiri introduction.
2. Umeboshi (pickled plum)
Umeboshi brings a sharp, salty, fruity tang that cuts through mild rice. Remove the pit, then chop or mash a small amount of the plum flesh. Because umeboshi can be intensely seasoned, begin with about ½ to 1 teaspoon per rice ball. Some people place one small piece in the center; others spread chopped plum through the rice for a bright, even flavor.
Check the package before adding extra salt. Umeboshi products vary, and some are sweeter or less salty than others. A little toasted sesame can soften the sharpness, while shiso is a natural aromatic companion. Avoid placing the pit inside the rice ball, since it is unpleasant to bite and can be a choking hazard.
3. Tuna mayonnaise (tsuna mayo)
Tuna mayo is creamy, mild, and popular with children and adults alike. Drain canned tuna very thoroughly, then stir it with Japanese mayonnaise or another mayonnaise you enjoy. For a small batch, combine about ½ cup well-drained tuna with 1 to 2 tablespoons mayonnaise. Add a tiny splash of soy sauce or a little black pepper if you like, but avoid making the mixture loose.
Use a teaspoon-sized portion in the center. Since it contains fish and mayonnaise, keep it chilled until assembly and refrigerate finished rice balls promptly if they will not be eaten soon. For the full recipe, see our Tuna Mayo Onigiri guide. To make the filling more textured, fold in finely sliced scallion; to add heat, use a small amount of chili sauce without thinning the mix.
4. Kombu (seasoned kelp)
Simmered kombu has a deep, savory taste that pairs naturally with rice. Use finely chopped tsukudani-style kombu or seasoned shredded kelp; both are concentrated, so a little is enough. Start with about a teaspoon in each rice ball, and taste before adding salt because packaged kombu can be quite seasoned.
For a two-texture version, mix a small spoonful of kombu into the rice and place another pinch in the center. Our Kombu Onigiri article goes deeper into this savory seaweed filling and how to shape it into a rice ball.
5. Okaka (bonito flakes and soy sauce)
Okaka combines dried bonito flakes with a small amount of soy sauce. The flakes absorb the seasoning and become a fragrant, savory filling. For six rice balls, toss roughly 1 cup of loosely packed bonito flakes with 1 to 2 teaspoons soy sauce. Add the sauce gradually; the flakes should be seasoned and just lightly moistened, not wet enough to drip.
Sesame seeds or finely chopped scallion can add texture. If you need a gluten-free filling, check the soy sauce label and choose a product specifically labeled gluten-free; bonito flakes are fish, so they are not suitable for people avoiding fish.
6. Tarako or mentaiko (salted or spicy cod roe)
Tarako is salted cod roe, while mentaiko is seasoned cod roe that is often spicy. Both have a briny, savory flavor and a soft texture. Check the package instructions to see whether the roe is ready to eat or should be cooked. If cooking, follow the product guidance, let it cool, then portion a small amount into each rice ball. A little roe goes a long way, especially when it is spicy or salty.
Try it with a little nori or sesame. Since roe products vary in seasoning and preparation, use the package information as your guide rather than assuming all types are interchangeable.
7. Shio kombu and furikake
Shio kombu is thinly cut, salted kelp that can be folded into warm rice. Furikake is a dry Japanese rice seasoning with many possible ingredients, such as sesame, seaweed, bonito, egg, or fish. These are convenient when you want to season the rice itself rather than make a separate center. Sprinkle a little in first, taste the rice, and add more only if needed; both can be salty.
Always read the ingredient panel if you have allergies or dietary restrictions. Furikake blends differ, and some contain fish, egg, soy, sesame, or other allergens.
Vegetarian and plant-based filling ideas
Vegetarian onigiri can be deeply savory, colorful, and satisfying. The most reliable fillings are cooked or pickled, finely cut, and drained. Think about contrast: a soft center with a little crunch, a bright tang against mild rice, or a nutty ingredient with herbs.
- Edamame and sesame: Lightly mash cooked edamame with toasted sesame, a little salt, and optional lemon zest. Keep some beans whole for texture.
- Shiitake or mixed mushrooms: Cook chopped mushrooms until their moisture evaporates, then season lightly with soy sauce. Cool before filling.
- Takana or pickled mustard greens: Chop and squeeze out excess brine. The tangy greens are flavorful in the center or folded into rice.
- Shiso and ume: Combine chopped shiso with a little pitted umeboshi for herbal freshness and acidity.
- Carrot and ginger: Cook finely diced carrot until tender and mix with a trace of ginger and sesame.
- Roasted sweet potato: Use small cubes of firm roasted sweet potato with sesame or a light miso seasoning. Avoid a wet mash.
- Avocado and sesame: Use a small firm piece, season lightly, and assemble just before eating because cut avocado browns and softens.
Some ingredients that seem convenient, like juicy cucumber or loose salsa, add too much water to the center. If you want a fresh element, serve it alongside the rice ball rather than inside. For more ideas about vegetarian rice balls and the differences between centers and mixed-in seasonings, see our published guide to whether onigiri is healthy, which also discusses how ingredient choices shape a meal.
More filling combinations to try
Chicken teriyaki
Use finely chopped cooked chicken coated in a thin teriyaki glaze. Let the sauce reduce until it clings to the chicken, then cool it completely. A teaspoon of chicken is usually enough. Too much sauce can make the rice slippery and difficult to seal. Add a little sesame or scallion if you want extra aroma.
Shrimp mayo
Chop cooked shrimp into small pieces and mix with a modest amount of mayonnaise, salt, and pepper. Drain and chill the mixture before using. The pieces should be small enough that they do not poke through the rice shell. For safety, keep the filling cold and do not leave finished onigiri with seafood or mayonnaise at room temperature for extended periods.
Egg and scallion
A firm omelet cut into small pieces makes a mild, tender center. Season lightly with salt or soy sauce, cool it, then combine with thinly sliced scallion. A moist, runny egg mixture is harder to enclose, so cook the egg fully and let it set before chopping.
Beef and ginger
Cook thinly sliced beef with ginger and a small amount of soy-based seasoning until the liquid has mostly evaporated. Cool and chop it finely. The sweet-savory flavor works well with plain rice, but use a restrained portion so the meat does not overpower the rice.
Spicy tuna or chili salmon
Fold a little chili paste into tuna mayo or mix chili with cooked salmon flakes. Add heat in tiny increments; the rice softens strong spice, but a little goes a long way. Keep the mixture thick and chill it until you are ready to assemble.
Start with a base (fish, beans, mushrooms, egg, or kelp), choose one accent (sesame, shiso, scallion, ginger, or chili), and add only enough seasoning to make the filling vivid. Two or three ingredients are often better than a crowded mixture.
Center filling, mixed-in rice, or an outside topping?
There are three useful ways to add flavor, and each gives a different eating experience.
- Center filling: A compact pocket keeps each ingredient distinct. It works best for flavorful mixtures, such as salmon, tuna mayo, umeboshi, or kombu. Use a little rice on your palm or plastic wrap, create a hollow, add the filling, then cover it fully.
- Mixed through the rice: This spreads flavor into every bite. Use dry or finely chopped ingredients like sesame, furikake, shio kombu, or finely flaked salmon. Fold gently so you do not mash the rice.
- Outside coating or topping: Nori, sesame, furikake, or thinly sliced greens add aroma and texture on the surface. Add crisp nori just before serving; steam from warm rice makes it soften over time.
You can combine methods, but keep the total seasoning moderate. For example, mix a small amount of sesame through the rice, add a center of salmon, and wrap the base in nori. That gives a distinct center, lightly seasoned rice, and a salty seaweed finish without overwhelming the bite.
How to prepare fillings that shape neatly
Keep every cooked filling cool
Hot filling can soften the rice and make shaping uncomfortable. Cook fish, meat, eggs, and mushrooms ahead of time, then let them cool before assembling. For perishable ingredients, cool and refrigerate promptly rather than leaving them on the counter to reach room temperature for a long time.
Drain liquids and trim large pieces
Drain tuna, blot oily fish, squeeze excess brine from pickled greens, and simmer sauces until they cling to their ingredients. Chop large items into small pieces so the filling sits in a compact mound. A smooth, spoonable center should hold its shape without dripping.
Shape with warm rice and damp hands
Use freshly cooked Japanese short-grain rice while it is warm enough to mold but not too hot to handle. Lightly wet your hands and use a small pinch of salt if desired. Press rice into a shallow cup, add the filling, cover it with rice, then close and shape with even pressure. Do not squeeze so hard that the finished rice ball becomes dense.
Plastic wrap can help beginners create an even shape and keep fillings off their hands. It is also useful for packing, but let steam escape before wrapping a freshly made rice ball for storage. For more shaping variations, molds, and rice tips, revisit the onigiri shaping guide.
Pairings: choose a filling for the moment
Think about when and how you will eat the rice ball. A simple umeboshi or salmon center travels neatly. Tuna mayo tastes rich and comforting, best kept chilled until close to mealtime. Kombu and okaka add a deeply savory bite beside soup. Vegetable fillings bring color and variety to a bento.
| If you want… | Try… | Add alongside… |
|---|---|---|
| Bright and tangy | Umeboshi with shiso | Cucumber or mild soup |
| Creamy and mild | Tuna mayo or shrimp mayo | Pickles and greens |
| Savory and roasted | Salmon or okaka | Miso soup or tamagoyaki |
| Deep umami | Kombu or mushroom | Steamed vegetables |
| Fresh and plant-based | Edamame sesame or takana | Fruit or a small salad |
For a warm, crisp variation, a sturdy filling can also go inside yaki onigiri. Our Yaki Onigiri guide explains how grilling changes the outside texture and why a compact filling helps the rice stay together.
Food safety for fish, meat, egg, and mayonnaise fillings
Cooked rice is perishable, and fillings such as fish, cooked meat, egg, and mayonnaise-based mixtures need careful handling. Wash your hands, use clean utensils, and keep cold ingredients refrigerated until assembly. FoodSafety.gov advises refrigerating perishable food, including cooked rice and leftovers, within 2 hours, or within 1 hour when the temperature is above 90°F (32°C). Its food safety guidance also notes that leftovers should be kept chilled and not left out beyond those time limits.
If packing onigiri for lunch, use an insulated lunch bag with a cold source for perishable fillings, and keep the rice balls cool until they can be eaten. Do not rely on smell or appearance alone to decide whether food left at room temperature is safe. When in doubt, follow local food safety guidance and discard food that has been held too long.
For a filling-free rice ball or a simple salted option, the handling is easier, but cooked rice still should not sit out indefinitely. If preparing ahead, store it promptly in a covered container and keep it cold. Nori can be packed separately and added just before eating to preserve its crisp texture.
Common filling problems and easy fixes
The filling leaks through the rice
Use a smaller spoonful, chop large chunks finer, and make the rice shell thicker around the center. Check that the rice is sticky enough and press the seam closed. Very oily, saucy, or wet fillings should be drained or reduced before use.
The rice ball falls apart
Use warm short-grain rice, wet your hands lightly, and shape with even pressure. Check that your rice is not dry or made from a long-grain variety that is less sticky. If the filling is chunky, make it smaller and keep it centered while shaping.
The center tastes too salty
Reduce the amount of concentrated filling, such as umeboshi, seasoned kombu, or soy-based okaka. Do not salt the rice heavily at the same time. Taste the filling by itself first so you can gauge its intensity before portioning it.
The flavor disappears into the rice
Choose a more concentrated center, increase the portion slightly, or move the filling from mixed-in rice to a central pocket. A small amount of sesame, shiso, or scallion can add aroma without requiring more salt.
Frequently asked questions
What is the most popular onigiri filling?
Popular choices include salmon, umeboshi, tuna mayo, kombu, and okaka. Preferences vary, and home cooks often choose what is available. If you are new to onigiri, make one salmon and one umeboshi rice ball to compare a savory filling with a tangy one.
Can I use leftover cooked fish or chicken?
Yes, as long as it was cooked and stored safely, and is still within its safe storage period. Flake or chop it finely, remove bones, cool it, and drain excess liquid. Keep it refrigerated until you assemble the rice balls.
Can I make onigiri with no filling?
Yes. Salted rice, rice with furikake, or plain rice wrapped in nori can be delicious without a center. A filling is one option, not a requirement. For a crisp exterior, try our linked Yaki Onigiri recipe.
Can I prepare the fillings in advance?
Many fillings can be prepared ahead, cooled, and refrigerated in a covered container. Keep seafood, meat, egg, and mayonnaise mixtures cold, and assemble the rice balls close to serving time for the best texture. Follow food safety time and temperature guidance.
What fillings are good for a vegetarian lunch?
Try edamame and sesame, mushrooms, pickled mustard greens, umeboshi, shiso, or seasoned kelp. Check labels on furikake and prepared seasonings, as they may contain fish, egg, or other ingredients that are not vegetarian.
Which fillings are best for beginners?
Salmon flakes, umeboshi, and seasoned kombu are easy to portion because you can use them in small amounts. Tuna mayo is another approachable option, though it needs to be kept cold. Begin with one filling at a time so you can get a feel for how much fits inside your rice.
Pick a flavorful base, keep it dry enough to hold together, add a little aromatic accent, and seal it inside warm short-grain rice. Start small, then adjust the next rice ball to your taste.
Find your favorite combination
Onigiri fillings can be traditional, simple, playful, or based on ingredients already in your kitchen. Salted salmon gives you a savory classic; umeboshi brings bright acidity; kombu and okaka deliver deep umami; tuna mayo makes a creamy, comforting center. Vegetables, eggs, and cooked meats open up even more possibilities.
Start with a small amount and keep the center compact. Drain wet ingredients, cool cooked fillings, and leave enough rice around the outside to seal everything in. Once you are comfortable with the shape, experiment with mixing seasonings through the rice or adding a crisp nori wrap just before serving. A few different fillings are all it takes to make a tray of rice balls feel like your own. 🍙
