Tuna Onigiri

Tuna onigiri is the easiest, simplest and quickest way to make a super delicious onigiri! I remember eating onigiri’s every morning when I was in Japan and would always make sure I had a tuna one.

These are great for a quick lunch at home or on the go! I love making these when I go on picnics or hiking. They’re so easy to make and can be made ahead of time too! If you’re making them in advance, just wrap the onigiri in plastic wrap and place it in the refrigerator. The plastic wrap will keep the moisture in and prevent the rice from drying out.

I assembled the onigiri with a little help from my favorite kitchen gadget – this Kirby onirigi mold! The mold made the process so much easier and the onigiri comes out perfect every single time. I highly recommend getting yourself a mold because it’s a big time saver!

Tuna onigiri is simple to make and only requires a few ingredients. But first, let’s dive into what onigiri is.

What is Onigiri?

Onigiri, also known as omusubi or rice balls, is a Japanese dish consisting of steamed white rice shaped into triangular or oval forms before being wrapped in nori (seaweed).

Tuna mayo, salted salmon, pickled umeboshi, katsuobushi, kombu, tarako, and other savory ingredients are commonly used to fill onigiri. Check out my Salted Salmon Onigiri here! These rice balls are ideal for taking on picnics since they’re easy to transport and tasty.

While onigiri is traditionally made with white short grain rice, brown rice or sushi rice can also be used. Recently, onigiri has become popular internationally, and there are now many different types of onigiri available, including vegan and gluten-free options. Check out my vegan Mushroom Onigiri recipe here!

Whether you enjoy it as a light meal or a tasty snack, onigiri is a delicious way to experience Japanese cuisine.

A Look At The History of Onigiri

Onigiri is one of the first travel-friendly foods in Japan. It is thought to have originated during the 11th century when a Japanese novelist known as Murasaki Shikibu wrote about people eating rice balls wrapped in bamboo sheaths while on long journeys.

During the war, soldiers were said to have carried onigiri with them as quick lunchtime meals. Onigiri was also eaten during the Edo period as a type of fast food but during this time, onigir was just a rice ball with a bit of salt.

Nowadays, onigiri has become a popular dish in Japan and can be found in convenience stores, supermarkets, and even some restaurants. It is now made with different fillings and flavors to suit everyone’s taste.

What Makes Onigiri So Delicious?

While this snack is quite simple, onigiri is exceptionally delicious. The rice is usually seasoned with salt, and the fillings add a burst of flavor. These are just some of the reasons why onigiri is so delicious:

Enhances the Flavor of the Rice

Onigiri is typically made with short-grain white rice or sushi rice. This type of rice is sticky and has a slightly sweet flavor. When the rice is mixed with salt, it enhances the sweetness of the rice and makes it even more delicious.

Additionally, the rice is sometimes mixed with a little bit of vinegar. This gives the rice a slightly tangy flavor that pairs well with the fillings.

The Fillings Add More Flavor

As I mentioned, onigiri is usually stuffed with savory fillings that add a ton of flavor!

The pickled umeboshi is sour and slightly sweet, while the katsuobushi is smoky and savory. The kombu adds an umami flavor, and the tarako is creamy and salty.

The combination of these flavors is what makes onigiri so delicious. You can get a mix of sweet, sour, salty, smoky, and umami in one bite.

Perfect For Any Occasion

Onigiri is perfect for any occasion because it makes a great quick snack or light meal. You can take it with you on the go or enjoy it at home.

It is also a popular dish to eat during festivals and other special occasions. In Japan, onigiri is often given as a gift during the New Year.

Where To Get Onigiri

There are many places where you can get onigiri. In Japan, onigiri is available at convenience stores, supermarkets, and restaurants.

If you’re not in Japan, don’t worry! Many Japanese restaurants offer onigiri. You can also find onigiri at your local Asian markets.

You can also make onigiri at home!

Different Shapes of Onigiri

Onigiri can be made into many different shapes. The most common shape is triangular, but onigiri can also be round, oval, or rectangular.

The shape of the onigiri is usually determined by the filling used. For example, triangular onigiri is often filled with salmon, tuna, or katsuobushi. Round onigiri is often filled with pickled umeboshi, and oval onigiri is often filled with kombu.

You can make onigiri into any shape that you like. The important thing is to have fun and be creative!

Common Ingredients Found in Tuna Onigiri

If you are planning on making tuna onigiri at home, here are some common ingredients that you will need:

  • Short Grain Rice: This is the most critical ingredient. You will need short-grain white rice or sushi rice. Alternatively, you can use any type of rice that you like.
  • Nori: Nori is a type of seaweed used to wrap onigiri. Nori is usually sold in sheets; you will need to cut it into strips.
  • Seasonings: This can vary depending on your preferences, but for this recipe you will need salt, Japanese sansho pepper (or ground black pepper), and furikake for garnish
  • Fillings: Similar to the seasonings, this is completely customizable. For this recipe, you’ll need canned tuna, Kewpie mayo, and scallions.

5 Helpful Tips For Making the Perfect Onigiri

If you’re new to making onigiri, here are a few helpful tips:

Tip #1: Always use fresh rice

It’s important to use fresh rice when making onigiri. Rice a day or two old will not stick together either, and it will be more challenging to work with.

If you can, cook the rice just before you make the onigiri. This will ensure that the onigiri turns out correctly.

Tip #2: Use your hands or a mold to shape the onigiri

Onigiri is traditionally shaped by hand however it does take practice!  With practice and time, it’s actually pretty easy to do.

To shape the onigiri by hand, first, wet your hands with some water. Then, take a small amount of rice and shape it into a ball. Once you have a rice ball, use your hands to mold it into the desired shape.

Remember to add pressure to the rice so that it sticks together. If the onigiri is too dry, you can wet your hands with water and add more moisture to the rice.

Tip #3: Use a mold shape the onigiri

If you’re pressed with time or you just don’t have the patience to make it by hand, you can use an onigiri mold which will make the process easier and more convenient! Personally, this is my preferred way of making a foolproof perfect onigiri every time.

I assembled the onigiri with my favorite kitchen gadget – this Kirby onirigi mold! The mold made the process so much easier and the onigiri comes out perfect every single time. I highly recommend getting yourself a mold because it’s a big time saver!

Tip #4: Do not overfill the onigiri, or it won’t be easy to eat or assemble

Fillings should be added sparingly and should not make up more than ⅓ of the onigiri. If you add too much filling, the onigiri will be difficult to eat and fall apart.

It’s important to have a good rice to filling ratio otherwise, it may be too bland or too salty. 

Tip #5: Onigiri can be made ahead of time

If you’re making onigiri in advance, just wrap the onigiri in plastic wrap (without the nori) and place it in the refrigerator. The plastic wrap will keep the moisture in and prevent the rice from drying out.

When you’re ready to eat it, wrap it with a fresh piece of nori and enjoy!

Frequently Asked Questions

Here are some of the most frequently asked questions:

How long will the tuna onigiri stay fresh?

Tuna onigiri is best eaten immediately after it is made. However, it will stay fresh for up to 24 hours if stored in the fridge. 

How should I store tuna onigiri?

Onigiri can be wrapped in saran wrap and stored in the fridge, if not eaten immediately.

Can traditional mayonnaise be used in place of Japanese mayonnaise?

Yes, you can use traditional mayonnaise in place of Japanese mayonnaise. However, the flavor will be slightly different. I highly recommend using Japanese Kewpie mayonnaise if you can find it! It’s richer and a little sweeter than regular mayonnaise. 

What kind of tuna should I use?

I recommend using canned tuna for this recipe. You can use any brand you like however, I prefer the Korean brand – Dong Wan. 

What other fillings can I use?

If you don’t like tuna, feel free to use another type of protein in its place. Chicken, salmon, and tofu are all excellent options. You can also add vegetables to the onigiri for a more well-rounded meal.

Tuna Onigiri

Servings 4 onigiri
Prep Time 10 minutes
Total Time 10 minutes


  • 3-4 cups cooked short grain rice
  • 1/2 tsp salt
  • 1 can of tuna drained
  • 2 scallions finely chopped
  • 2 tbsp mayo preferably Kewpie mayo
  • dash of Japanese sansho pepper or ground black pepper
  • furikake for garnish
  • nori sheets


  • In a bowl, combine cooked short grain rice and salt. Mix together well and set aside to cool down.
  • In another bowl, mix tuna, scallions, mayo, and sansho pepper. Mix until well combined.
  • Next, assemble the onigiri. If using a mold, follow the instructions on the package.
  • If you're shaping by hand, start by wetting your hands with water first so the rice doesn't stick. Grab about 1/4 cup rice and flatten it out on your palms. Place 1-2 tbsp of the tuna filling in the center. Top with some more rice and press it down so the rice on top sticks to the rice on the bottom. Using your palms, apply pressure on all sides and shape the onigiri into a triangle. This may take some practice and a few tries.
  • When you're happy with the shape, wrap a sheet of nori on the underside of the onigiri. Dip or sprinkle the furikake on top and enjoy!
  • *Onigiri's can be made in advance and can be eaten cold too! To serve the next day, wrap the onigiri in plastic wrap and place in the refrigerator. The plastic wrap will keep the moisture in and prevent the rice from drying out*
Course: Appetizer, Dinner, Lunch, Snack
Cuisine: Japanese

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