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If you’ve ever been to Japan, you will know what it’s like to bite into that very first tuna and mayo rice ball and just being blown away by how good this simple combination of ingredients can be! Today, I’m going to show you how to make a tuna and mayo rice ball that’s just as good as the convenience store ones!
Watch how to make tuna mayo onigiri
What is a tuna mayo onigiri?
Onigiri are Japanese rice balls. They’re made with short-grain Japanese rice that is stickier than long grain varieties. This allows the rice to be shaped into a ball, or in a triangle, which is the Japanese preferred shape.
The rice ball is filled with different, mostly-savory ingredients. Traditionally it would be a pickled plum, a bit of grilled salmon, or a sweet and savory seaweed mixture called “hijiki”.
Tuna mayo onigiri is, as its name implies, filled with tuna and mayonnaise. This is actually the most popular filling for onigiri, and if you’ve never had a rice ball before, this would be the one that you would be the most familiar to you, taste-wise.
How do you make a tuna mayo onigiri?
If you were to make your own rice ball with canned tuna and mayonnaise, you may be underwhelmed or even disappointed. The Japanese tuna mayo onigiri have such an amazing depth of flavor that homemade onigiri just don’t have.
One thing that the Japanese use is Japanese-style mayo. You may have heard of the ubiquitous ‘Kewpie mayonnaise’. It’s a Japanese mayo brand with a small naked baby as its mascot.
As strange as that may be, it doesn’t take away form the fact that it’s SO much better than our American mayo! It’s creamier, lighter, richer, and just plain better tasting overall!
I honestly can’t stand American mayo. It feels heavy, greasy, the smell is overwhelming, and looking at a jar of it just makes my stomach churn. But if you put some Kewpie mayo in front of me, I will literally squeeze some on almost anything.
So what makes Kewpie so different from your typical jar of Hellman’s? First, Japanese mayo is made with only egg yolks, compared to the whole egg of American mayo.Â
Second, instead of using white distilled vinegar, which is harsh and overpowering, Kewpie uses rice wine vinegar which is slightly sweet and much mellower. Finally, Kewpie has a healthy dose of MSG just to give your taste buds a kick.
But it doesn’t just stop at switching out the Hellman’s for Kewpie. You’ve also got to use Kakushi Aji.
The Secret To Better-Than-Japanese-Convenience-Store Tuna Mayo Onigiri
Kakushi Aji literally translates to “hidden taste”. This is a concept that the Japanese use in almost all their cooking. For instance, Japanese curry includes onions, vegetables and spices to make a flavorful stew. However, a lot of restaurants and even home chefs will add in a small amount of chocolate to give the curry depth and bitterness.
The amount added is imperceptible to even the most well-trained of taste buds, but adds more depth to the curry and gives it that “something” that helps it to stand out.
So in order to make a great tuna mayo onigiri, you need to add kakushi aji. For our tuna mayo onigiri, we’re adding three ingredients to really bump up the flavor of our onigiri and make it taste so much better than what you’d actually get on the Japanese convenience store shelves:
1) Soy Sauce
If it’s a Japanese dish, you can safely assume that there’s some soy sauce in there, and that’s exactly what we’re adding to our tuna mayo onigiri. It will give saltiness and savoriness to our rice ball.
2) Powdered dashi
Dashi is the quintessential Japanese flavoring stock. It’s often made with konbu seaweed (which gives it umami) and katsuobushi, which is a smoked and dried fish that’s then shaved paper-thin. The dashi will give our filling more salty savoriness, along with a unique smoky flavor.
3) Ketchup
Surprised? I sure was! But the secret is that you’re not supposed to add so much ketchup that you can taste it. We’re only adding just enough to give some tang and sweetness to the filling.
In fact, if your filling tastes strongly of any of the three ingredients, you’ve definitely added too much! Remember, this is hidden taste!
How to get that beautiful triangle shape
Japanese onigiri have a triangular shape, despite the name and that helps it to stand out from other rice balls.
 Korea has its own version of rice ball called Jumeokbap that are literally balls of rice with the filling mixed in. They’re really easy to make and I highly recommend that you give them a try some time!
So in order to get that proper triangle shape that the Japanese rice balls have, it’s quite easy. Get your hands wet and grab a pinch of salt and rub it all over your hands. This will keep the rice from sticking to you and will also flavor the outside of the rice ball.
Grab a handful of rice and flatten it in the palm of your hand.
Next, place a generous amount of filling in the middle. Remember, we’re making an onigiri that’s better than the convenience store’s, so don’t skimp!
Grab a small handful of rice and add in top of the filling and begin to slowly work the rice around the filling.
Shaping it into an oval, cup your free hand into an angular shape and place it on top of the oval. Give it a gentle squeeze and you should see a rough triangle forming.
Rotate the rice ball so that the top of the triangle continues to point upwards, then gently squeeze. You want to continue rotating and squeezing the shape until you get a beautiful triangle.
Finally, wrap it with seaweed and top it with some of the extra filling, just so you know what’s in it!
Tuna Mayo Onigiri Ingredient Checklist
- Japanese Short-grain Rice (See it on Amazon) – Short-grain rice that’s perfect for Korean rice balls
- Canned tuna
- Kewpie Japanese Mayo (See it on Amazon) – The world’s greatest mayonnaise!
- Soy Sauce (See it on Amazon) – My favorite brand!
- Dashi powder (See it on Amazon) – This powdered Japanese seafood stock will add great savory and smokey flavor to your rice balls. This is also used in some of my other recipes like my Japanese gyudon rice bowl!
- Nori Seaweed Sheets (See it on Amazon)
Japan's Most Popular Rice Ball!
When you take a bite of this, you will understand why the Japanese love this rice ball the most! That savory, smoky, addictive flavor will make this a favorite in your house!
Make sure you check out some of my other delicious Japanese recipes! I know you’ll absolutely love them!
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Tuna Mayo Onigiri
Ingredients
- 3 cups cooked short-grain rice
- 2 sheets of nori seaweed
- Water
- Salt
Tuna Mayo Mixture
- 5 oz canned tuna
- 1 tsp soy sauce
- 1/2 tsp dashi powder
- 3 heaping tbsp Japanese kewpie mayonnaise
- 1 tsp ketchup
Instructions
- Mix the *Tuna Mayo* ingredients and set aside.
- Tear the nori seaweed along the third perforated line. You should have a 4-inch wide strip. Do the same with the rest of the nori seaweed until you end up with three wide strips. Set aside.
- Wet hands and add a pinch of salt. Grab a handful of rice and flatten it out.
- Add a generous heaping of tuna mayo and add a bit more rice onto the filling. Shape the rice into an oval, ensuring that the filling is in the middle of the rice ball.
- Place the rice ball into your cupped palm. Cup your free hand into and angle and place on top of the rice ball and squeeze gently.
- Rotate the rice ball about 120 degrees (so that the tip of the triangle is pointed up), and squeeze again. Continue to rotate and squeeze gently until a uniform triangle shape forms.
- Repeat steps 3 - 6 with the remaining rice and tuna mixture.
- Place the rice ball in the middle of the seaweed strip and fold the top corners inward, towards the middle of the rice ball. Use a grain of rice to hold the seaweed together if necessary.
- Tuck the bottom of the seaweed underneath the seaweed and set aside. Continue with the rest of the rice balls.
- Garnish the tops of the rice ball with remaining tuna may mixture and serve immediiately.
Hi Ken! Do you use tuna packed in water or oil? Thanks for your recipes! I have made your karaage, gyudon and katsu sando so far and plan to cook my way through pretty much your whole YouTube channel.
Hi Taylor! I use tuna packed in water. Oil-packed tuna is tastier in my opinion, but because mayo is being added to the recipe anyway, it’s kind of overkill. Thanks so much and I hope you find some new favorite recipes here!