Spicy Tuna Onigiri are Japanese rice balls made with sticky short-grain rice filled with a spicy Kewpie-mayonnaise tuna mixture and wrapped in savory nori. Compact and portable, they make a satisfying snack or lunch item. Follow these clear steps to assemble a batch in under an hour.
What is Onigiri?
Onigiri is a classic Japanese snack of seasoned sticky rice shaped into rounds or triangles and often wrapped with a strip of nori. Easily packed into bento boxes or enjoyed on the go, onigiri pairs well with soups, salads, or other Japanese dishes.
About Spicy Tuna Onigiri
- Taste – The spicy tuna filling is bold and savory, balanced by plain salted rice and the light brininess of nori.
- Texture – Creamy, flaky tuna contrasts with the soft, slightly chewy rice and crisp-on-contact nori.
- Effort – Simple to prepare and fun to assemble, onigiri is a hands-on recipe that’s great for cooking with others.
- Time – Rice cooking takes about 30 minutes (or follow your rice cooker). Mixing the tuna and shaping the onigiri takes roughly 20 minutes.
Ingredients
Tuna Onigiri
- Rice – Japanese short-grain rice is ideal: sticky enough to hold shape while remaining tender. Lightly salt the cooked rice for flavor.
- Nori – Dried seaweed sheets wrap the onigiri, add umami, and provide a convenient handle.
- Canned tuna – A convenient, hearty filling that mixes well with the spicy mayo.
- Black sesame seeds – Optional garnish for a mild nutty flavor and visual contrast.
Spicy Kewpie Mayo
- Kewpie mayo – Japanese-style mayonnaise with a rich umami flavor and creamy texture; the base of the spicy mayo.
- Sriracha – Adds controlled heat without overpowering the filling.
- Sesame oil – A small amount brings a toasty, nutty aroma.
- Mirin – A touch of sweet rice wine deepens umami and rounds the sauce.
See the recipe card below for exact quantities used.
Substitutions
- White sesame seeds – Swap for black sesame if you prefer a milder look and flavor.
- Brown rice – You can use Japanese brown rice for more fiber; cook with extra water and ensure it’s sticky enough to form.
- Sushi rice – If you like seasoned rice, use sushi rice (vinegar-seasoned) for a tangier profile.
- Miso sauce – For a different umami note, replace the spicy mayo with a light miso glaze.
Variations
- Furikake – Sprinkle furikake on the rice or mix into the filling for extra flavor layers.
- Spam musubi – A Hawaiian-style variation featuring cooked spam pressed with rice and wrapped in nori.
- Yaki onigiri – Grill or pan-sear the shaped onigiri and brush with soy or miso glaze for a crispy exterior.
- Extra spicy – Increase Sriracha or add togarashi to the spicy mayo for more heat.
Instructions
- Make the rice – Rinse 1½ cups Japanese short-grain rice under cold water until it runs clear. Combine rice with 2 cups filtered water in a pot and bring to a low boil. Reduce heat, cover, and simmer 20 minutes or until water is absorbed. Remove from heat and let rest 10 minutes, then fluff. Alternatively, cook in a rice cooker following manufacturer instructions.
- Prepare the tuna filling – While the rice cooks, drain 4 oz canned tuna into a bowl. Mix with 1 tablespoon Kewpie mayo, 1 teaspoon Sriracha, ½ teaspoon sesame oil, 1 teaspoon mirin, and 1 tablespoon furikake. Break the tuna into flakes and combine until evenly coated.
- Shape the onigiri – Let the hot rice cool until warm. Keep a small bowl of water nearby and wet your hands to prevent sticking; sprinkle a little salt on your palms. Place a handful of rice in your hand, make an indentation, spoon in about 1 tablespoon of tuna filling, then cover with a little more rice. Gently shape into a compact ball, then form into a triangle by angling the sides into points. Avoid pressing too tightly to keep the texture tender.
- Wrap and finish – Wrap each onigiri with a strip or small sheet of nori. Roll in toasted sesame seeds if desired. Serve immediately or pack into a bento for later.
Pro tip – Keeping your hands moist while shaping prevents rice from sticking and makes shaping much easier.
What to Serve with Onigiri
Enjoy tuna onigiri alone as a snack or alongside sides for a fuller meal. Good companions include grilled vegetables, simple salads, pickles, or a bowl of miso soup. They also complement sushi rolls and other Japanese-inspired dishes.
Other Onigiri Fillings
Onigiri can be filled with many ingredients. Popular options include:
- Sujiko – Salmon roe for a briny pop.
- Ume – Pickled plum (umeboshi) offers sweet, salty, and tart notes.
- Okaka – Bonito flakes mixed with soy for a simple, savory filling.
- Beef – Shredded, seasoned beef for a heartier, meat-based option.
- Kombu – Simmered kelp that brings a deep umami flavor.
- Plain tuna – Omit the spicy mayo for a milder tuna onigiri.
Recipe FAQs
Use Japanese short-grain sticky rice and shape the onigiri while the rice is still warm. Long-grain rice lacks the starch needed to bind, and cold rice will not hold its shape as well.
The triangle shape is traditional and practical: it’s easy to hold, packable, and—according to legend—evokes the protective shape of mountains.
Yes. Replace tuna with fillings like mushrooms, sweet potato, pickled plum (umeboshi), or other seasoned vegetables for a vegetarian version.
Equipment
Basic kitchen tools are all that’s needed: mixing bowls, a pot or rice cooker for rice, a rice paddle or spatula, and optionally an onigiri mold for consistent shapes.
Storage
Store onigiri in an airtight container or wrapped tightly in plastic in the refrigerator for up to 3 days to prevent drying. They do not freeze well. For packed lunches, use plastic wrap or a bento box to keep them fresh.
Top Tips
- Cool the steamed rice slightly before adding fillings and nori so the seaweed does not become soggy.
- Don’t press the rice too hard when shaping; a gentle, compact shape preserves a pleasant texture.
- Keep a bowl of water handy to wet your hands and prevent sticking while shaping.
Related Recipes
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Chicken Katsu Curry (Japanese Chicken Cutlet Curry)
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Shrimp Tempura Udon (Japanese noodle soup)
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Spicy Ahi Poke (Spicy Tuna Bowl)
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Furikake Salmon
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📖 Recipe
Spicy Tuna Onigiri (Japanese Rice Balls)
Equipment
- Mixing bowls
- Pot or rice cooker
- Rice paddle or spatula
- Optional: onigiri mold
Ingredients
- 1½ cups Japanese short-grain rice
- 2 cups filtered water
Filling
- 4 oz canned tuna, drained
- 1 tbsp Kewpie mayo
- 1 tsp Sriracha
- ½ tsp sesame oil
- 1 tsp mirin
- 1 tbsp furikake
- 1 sheet nori, cut into 8 pieces (or pre-cut nori)
- Toasted sesame seeds (optional)
Instructions
Rice
- Rinse the rice until water runs clear. Combine rice and filtered water in a saucepan. Bring to a low boil, reduce heat, cover, and simmer 20 minutes or until water is absorbed. Let sit covered 10 minutes and fluff. Or cook in a rice cooker per its instructions.
Spicy Tuna Onigiri
- Make the tuna: In a bowl, mix drained tuna with Kewpie mayo, Sriracha, sesame oil, mirin, and furikake until flaky and combined.
- Assemble: Let cooked rice cool until warm. Wet your hands and sprinkle a bit of salt on your palms. Place a handful of rice in your hand, create an indentation, add about 1 tablespoon tuna, cover with more rice, and shape into a triangle.
- Wrap: Wrap each onigiri with nori, roll in sesame seeds if desired, and serve.
Notes
Storage: Refrigerate in an airtight container or wrapped in plastic for up to 3 days. Keep moisture sealed to prevent drying. Not recommended for freezing.
Top tips: Keep hands wet when shaping, cool rice slightly before adding nori, and avoid over-compressing the rice.
Nutrition
Per serving: Calories 155 | Carbs 28 g | Protein 5 g | Fat 2 g