Bring memories of 7-Eleven home! This tuna mayo onigiri has a perfect tuna-mayo balance, with dashi and sugar adding rich flavor to this simple rice ball.
If you’ve been to Japan, you’ve probably tried 7-Eleven’s tuna mayo onigiri—my husband loves it and grabs one (or more) every visit!
I created this recipe to bring that flavor home, with a few twists: creamy Kewpie mayo, dashi-infused rice, and a hint of sugar to balance the tuna.
I hope you enjoy it as much as he does—warning: it might spark a craving for Japan! 😜
In This Post
Jump to Recipe✏️What is Onigiri? What is Tuna Mayo?
Onigiri is a rice ball that originated in Japan. It’s typically made from white rice and filled with various ingredients, such as salmon, tuna, kombu, or ume (pickled plum).
Onigiri is great to bring for lunch! With a protein-packed filling, it makes for a balanced meal of carbs and protein.
Tuna Mayo is a Japanese word shortened from “tuna” and “mayonnaise”—literally what the ingredients are, haha. It’s one of the most popular onigiri fillings in Japan!
🛒Ingredient Highlights
- Japanese rice: Use short-grain or medium-grain rice for onigiri (also known as sushi rice). You can use brown rice if you want, but it might be harder to shape the onigiri because brown rice is less sticky than white rice.
- Japanese mayonnaise: Japanese mayonnaise is richer and creamier than American mayonnaise, creating a deliciously creamy filling that everyone loves. You can find Japanese mayonnaise at your grocery store, online, or at Costco.
- Canned tuna: I used tuna packed in water, but you can use the one in oil too—it actually tastes better! (I always use the one in water, and it still tastes amazing.)
- Dashi powder: Use dashi powder made with only natural ingredients. My all-time favorite is Kayanoya Dashi.
🍳Let’s Cook Together!
1. cook rice
Rinse, soak, and cook rice.
2. Make the filling
Combine all tuna mayo ingredients in a small bowl.
3. mix dashi and rice
Mix dashi powder into warm cooked rice.
4. Shape the onigiri
Wrap with nori seaweed if desired
🍙How to Make an Onigiri Triangle?
You can shape onigiri using either your hands or plastic wrap, but here, I’ll show you how to do it with plastic wrap.
With your bottom hand, form the base edge of the triangle, while your top hand shapes the peak of the triangle.
Keep your bottom hand steady and use your top hand to rotate the rice, pressing it into a triangle shape in 3–5 turns.
Don’t apply too much pressure; think of gently gathering the rice towards the center.
💡Pro Tip: If you’re using an onigiri mold, go for one that shapes the rice gently without squishing it too much. Something like the TIKUSAN Onigiri Mold Musubi Maker is a great option—it’s easy to use and keeps your rice light and fluffy!
💌If you created this recipe and liked it, please let me know by leaving a comment below or tagging me on Instagram (@giveme.umami). I’d love to see your creation!
Easy Japanese Tuna Mayo Onigiri (with Spicy Option)
Ingredients
- 1 cup uncooked Japanese short-grain white rice (240ml, note 1)
- 1 cup + 2 tablespoons water (266ml)
- 1 teaspoon dashi powder (note 2)
- kosher salt
For the Tuna Mayo
- 2.5 ounces canned tuna (drained, about half of a small American canned tuna)
- 2.5-3 tablespoons Japanese mayonnaise
- ¾ teaspoon soy sauce
- ½ teaspoon granulated sugar
- ⅛ teaspoon ground black pepper
Instructions
- Rinse 1 cup uncooked Japanese short-grain white rice about three times until the water is clear.
- Cook the rice– Using a Rice Cooker or Slow Cooker: Transfer rinsed rice and add 1 cup + 2 tablespoons water to the cooker. Soak for at least 30 minutes, then start the cooker and let it finish as per settings.– Using a Pot on the Stovetop: Transfer rinsed rice and add 1 cup + 2 tablespoons water to the pot. Soak for at least 30 minutes. Cover and heat on medium until it boils, then reduce to low and simmer for 15 minutes. Turn off heat and let steam, covered, for 10 minutes. (Avoid lifting the lid while cooking.)
- Fluff the rice to release extra steam.
- Make tuna mayo: Drain and press 2.5 ounces canned tuna well to remove as much water from the tuna as possible. Add 2.5-3 tablespoons Japanese mayonnaise, ¾ teaspoon soy sauce, ½ teaspoon granulated sugar, and ⅛ teaspoon ground black pepper and mix well. The tuna mayo should look creamy.
- Mix dashi and rice: Add 1 teaspoon dashi powder to the cooked rice and mix well.
- Shape the onigiri (note 3): You can choose to shape the onigiri using your hands or plastic wrap. If using hands, wet your hands and sprinkle a tiny pinch of salt. If using plastic wrap, sprinkle a tiny pinch of salt on the wrap. Divide the rice and tuna mayo into individual servings. For each onigiri, place ⅔ of the rice in your palm or plastic wrap, top with tuna mayo, then cover with the remaining rice. Shape into triangles by pressing and turning.
- Enjoy: Wrap with nori seaweed if desired.
Notes
🗄️Storage Tips
I recommend eating tuna mayo onigiri on the same day, as the flavor and texture can change after being stored in the fridge or freezer.
Leftovers can be wrapped in plastic wrap for storage, but make sure to remove excess water from the tuna to avoid soggy onigiri.
- Fridge: Store for up to 1-2 days.
- Freezer: Store for up to 2 weeks.
🥢What to Serve with Onigiri
Serve tuna mayo onigiri with miso soup and some easy side dishes to make an onigiri teishoku!
(Teishoku is a Japanese set meal that typically includes rice, soup, a main dish, and side dishes, making it a balanced and satisfying option.)
❓Frequently Asked Questions About This Recipe
Simply add your favorite hot sauce or chili paste to the tuna mayo. I like to add 1 teaspoon of sriracha per 4 servings of tuna mayo.
I recommend making the onigiri on the day you plan to pack it for lunch, as storing them in the fridge makes the rice hard and dry. That said, you can make the onigiri the night before and pack it for lunch! Keep them cool with ice packs and consume them within 6 hours.
I serve onigiri at room temperature. If you’ve stored the onigiri in the fridge, leave it out until it returns to room temperature before eating.
Nori seaweed gets soggy due to the moisture from the rice. To keep it crispy, wrap the onigiri with nori right before eating.
Japanese short- or medium-grain rice (also known as sushi rice) is perfect for onigiri because it’s stickier than other types of rice, like basmati. You can use brown rice too, but it might be harder to shape because it’s less sticky than white rice.
