When I lived in Japan one of my favorite convenience store snacks was the spicy tuna onigiri from either 7-11 or Lawson. Unlike most places, in Japan the convenience stores actually have good food and nothing hits the spot quite like a spicy tuna rice ball in between bar hopping in Golden Gai!
Onigiri is simply a rice ball, commonly pressed into the signature triangular shape. However you will also see them as a spherical ball or a cylindrical tube, so don’t get hung up if you cannot get them into a nice triangle when you make this spicy tuna onigiri at home!
Traditionally onigiri were filled with things like pickled plum or salted fish, but these days people pretty much put whatever they want in them. While a spicy tuna onigiri isn’t traditional, it has been around since at least the 90’s when I first went to Tokyo to visit family.
How To Make Triangular Onigiri?
The easiest way to make perfectly triangular onigiri is to use a mold. You can find plenty of them online and many of them have cute characters on them. This is because homemade onigiri is commonly a bento-box addition and kids like cute things.
You can also do it by hand, which I will show below. This is more difficult and a little messier, but once you get the hang of it you shouldn’t have any problems making these spicy tuna onigiri perfectly triangular.
How To Make Spicy Tuna Onigiri
To make a spicy tuna onigiri at home you only need a few traditional ingredients plus the stuff for the filling. I also border my Japanese rice balls with a homemade furikake but this is entirely optional.
Ingredients For The Rice Ball
- 1 cup Rice – you have to use a short grain rice with a lot of starch. If you have a preferred brand of sushi rice you can use that, but any short, starchy rice will make a fine sticky rice for the onigiri.
- 2 cups Water – for the rice. Plus however much water you need to use for rinsing the rice beforehand.
- 1 sheet Nori (roasted seaweed sheets) – cut in half, and then cut in strips about 2.5 cm or 1 inch wide
- Furikake – this is a common Japanese rice seasoning blend. I use a homemade noritama furikake blend, but any style will work well in this onigiri recipe. Not to mention it is also entirely optional. It just adds some extra flavor to this spicy tuna onigiri.
Ingredients For The Spicy Tuna Filling
- 250 grams Tuna – you can get lower quality tuna, or even tuna scrap from your fishmonger if you are in a coastal area. Since it will be mixed with a bunch of other stuff there is no need to waste money on expensive toro tuna or other high quality cuts.
- 2 tbsp Japanese Mayonnaise – the most popular brand is Kewpie, but you can make a homemade Japanese mayonnaise if you can’t find the store-bought version.
- 1 tsp Sesame Oil
- 1 tbsp Soy Sauce
- Hot Sauce – to taste. You can use pretty much any hot sauce you like, from homemade hot sauce to store-bought. A commonly used option is Sriracha, but go ahead and get creative if you feel like it.
- Salt – to taste. It is likely you don’t need it as the soy sauce adds enough salt, not to mention the furikake for the rice, but I’ll list it as an optional ingredient anyways for those sodium fiends.
How To Cook The Rice For Onigiri
Place your rice in a strainer and run it under the faucet until the water runs clear. You want to clean off all the extra starch and dust. Then place the rice in a pot with the two cups of water. Bring the water to a simmer, then reduce to minimum and cover with a lid for 16 minutes.
OR: Just use a rice cooker. Seriously they are so efficient and always make perfect rice. My favorite brand is Zojirushi but honestly any quality one will be perfectly fine.
Making The Spicy Tuna Onigiri
The first thing you can do while the rice is cooking is to finely mince your tuna. I do this by hand with a chef’s knife, but you can also run it through a mincer or food processor. Just note that the later options have a tendency to make it into more of a mince while I prefer chunks.
Add in the Japanese mayonnaise, sesame oil, soy sauce, and the hot sauce of choice. Adjust seasonings as needed after tasting a little bit.
To make these spicy tuna onigiri without a mold I highly suggest using the plastic wrap method. Lay down a sheet of plastic wrap and place a handful of rice in the center. Make a divot and add about a heaping teaspoons worth of spicy tuna filling in the middle.
Next, get your hands under the plastic and fold the rice into a ball. You can try to shape it into a rough triangle here, but in the next step I’ll show how to get perfect corners.
I flatten the rice ball with the palm of my hand, and use the last two fingers to get the corners. Just spread your pinky and ring finger and press the rice ball into it. Try to press with gentle, even force so you don’t shove into the center filling.
Lastly open the plastic and spread some of the furikake on two sides of the triangle. Then press your seaweed strip around the bottom so you can easily lift the onigiri off the plastic and onto a serving platter. Enjoy!
If you are making these spicy tuna onigiri to eat later in say, a bento box then you can wrap them back up in plastic. The seaweed might get a little soggy due to the steam and moisture from the rice, but it will still taste great! You can also just keep the nori strips separate and add it right before eating.
What Else Can You Put In Onigiri?
Aside from the traditional pickled plum filling, here are a few other iterations of this classic Japanese rice ball snack:
- Japanese Potato Salad
- Braised Eel
- Sweet Shrimp with Mayonnaise
- Fish Eggs (Roe)
- Tempura Shrimp or Vegetables
- Kakuni (Braised Pork)
- And more!
Spicy Tuna Onigiri
- 1 Pot
- 1 Bowl
- 1 Knife
- 1 Onigiri Mold | optional
- 1 cup Rice if you have a preferred brand of sushi rice you can use that but any short, starchy rice will make a fine sticky rice for the onigiri.
- 2 cups Water for the rice. Plus however much water you need to use for rinsing the rice beforehand.
- 1 sheet Nori roasted seaweed sheets – cut in half, and then cut in strips about 2.5 cm or 1 inch wide
- Furikake this is a common Japanese rice seasoning blend. I use a homemade noritama furikake blend but any style will work well in this onigiri recipe. Not to mention it is also entirely optional. It just adds some extra flavor to this spicy tuna onigiri.
Ingredients For The Spicy Tuna Filling
- 250 grams Tuna you can get lower quality tuna or even tuna scrap from your fishmonger if you are in a coastal area. Since it will be mixed with a bunch of other stuff there is no need to waste money on expensive toro tuna or other high quality cuts.
- 2 tbsp Japanese Mayonnaise the most popular brand is Kewpie but you can make a homemade Japanese mayonnaise if you can't find the store-bought version.
- 1 tsp Sesame Oil
- 1 tbsp Soy Sauce
- Hot Sauce to taste. You can use pretty much any hot sauce you like from homemade hot sauce to store-bought. A commonly used option is Sriracha, but go ahead and get creative if you feel like it.
- Salt to taste. It is likely you don't need it as the soy sauce adds enough salt not to mention the furikake for the rice, but I'll list it as an optional ingredient anyways for those sodium fiends.
- The first thing to do is to wash your rice well and then cook it. If you are using a rice cooker then just follow your machines instructions. To make it in a pot add the washed rice and water to a pot and bring to a simmer. Once simmering reduce heat to minimum and cover with a lid. Let sit for 16 minutes then take off the heat.
- While the rice is cooking you should make the filling. Finely mince your tuna with a knife and place it in a bowl. Add the mayonnaise, soy sauce, sesame oil, and hot sauce of your choice to taste. Give everything a good mix and taste a bit to see if you should adjust anything.
- When the rice is done you can get to forming the onigiri. If you are using a mold just use that and skip the rest of the instructions. If you don't have a mold then continue reading.
- Lay down a sheet of plastic wrap on a flat surface. Place a handful of rice in the center and flatten a bit while making a divot in the center. Place a heaping teaspoon of spicy tuna filling in the divot.
- Get your hands under the plastic and bring up to close the ball.
- Flatten a bit with your palm and use your pinky and ring finger to shape the corners for the signature triangular shape (see photos above in article for reference).
- Open the plastic wrap and press some furikake onto two of the sides of the triangle. Then wrap your strip of nori on the bottom and remove the onigiri to a serving platter or plate. Enjoy!