Bento Box Ideas: Tuna Mayo Onigiri and Tamagoyaki

Looking for an easy bento idea? This one features tuna mayo onigiri and tamagoyaki—two classic Japanese favorites. Most of the prep can be done the night before, so in the morning all you have to do is shape the onigiri, pack it up, and enjoy a tasty meal at work or school!

Looking for more? Check these simple onigiri bento ideas!

🍱 What’s in This Onigiri Bento

This bento is simple, colorful, and packed with a variety of side dishes. Here’s what’s inside:

Tuna mayo onigiri: A classic combo of tuna and Japanese mayo wrapped in rice and nori. (Find more onigiri filling ideas!)
Tamagoyaki: A simple Japanese rolled omelet, a bento staple.
Broccoli goma-ae: Steamed broccoli tossed in a nutty sesame dressing for a flavorful veggie side.
Potato salad: Creamy Japanese-style potato salad with mashed potatoes, carrots, and a hint of mayo.
Cherry tomatoes: These are your bento’s little color boosters! Always nice to have on hand.

Prepping & Leftovers

To save time in the morning, prep most of the dishes the day before. Make the onigiri fresh in the morning for the best taste and texture.

Tuna mayo onigiri: Rinse and soak the rice the night before, then cook it in the morning (or use frozen rice and reheat). You can mix the tuna and mayo the night before or quickly in the morning.
Tamagoyaki: Make it the night before, let it cool, and store it in the fridge.
Broccoli goma-ae: Steam the broccoli and dress it the night before.
Potato Salad: Make this a day ahead and refrigerate.
Cherry Tomatoes: Wash and dry them ahead of time.

How to Make Onigiri Bento: Step-by-Step

Step 1

Let the freshly cooked rice cool down. Reheat the tamagoyaki, then let them cool completely.

Step 2

Place the rice onto a sheet of plastic wrap, add the tuna mayo filling in the center, then wrap and shape it into an onigiri. (Use an onigiri mold or case for easy shaping.)

Step 3

Once the onigiri is shaped, unwrap it and add a strip of nori around the rice.

Step 4

Arrange the side dishes neatly into your bento box.

Packing Tips

Bento is usually packed in the morning and eaten later, meaning it stays at room temperature for hours. That’s why it’s important to pack it in a way that keeps the food safe and fresh, especially during hot weather. Here are a few simple tips!

Use plastic wrap to shape the onigiri—it’s more hygienic, especially in warm weather.
Reheat leftovers thoroughly to kill any bacteria that could cause spoilage.
Cool all items completely before sealing the bento box to prevent condensation from forming.
Drain excess moisture from high-water items, such as pickles, using paper towels before packing.
Use dividers or silicone cups to keep wet and dry foods separate, maintaining freshness and texture.

No More Squished Onigiri!

If you toss an onigiri into your bag, it’ll likely get squished and lose its shape. That’s when an onigiri case comes in handy! It helps keep your onigiri in shape and doubles as a mold, so you can quickly make perfectly shaped rice balls. You can find them at 100 yen shops, such as Daiso, so be sure to check them out!

The pink onigiri case features Kuromi-chan, and the purple one has Cinnamoroll—my daughter’s favorite Sanrio character!

Bento Carrying Tips

Once everything is packed, wrap your bento box, onigiri, and chopsticks in a cloth—it’s not only handy for carrying, but can also be used as a placemat when it’s time to eat.

If you’re packing the bento during warm weather and it will sit at room temperature for several hours, be sure to use an ice pack or an insulated lunch bag to keep it fresh and safe.

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