Name: How To Reheat Onigiri
Prep time: 1 min
Cook time: 1 min
Total time: 2 min
Ingredients: 1 piece onigiri

Table of Contents

Have you prepared or brought home too many onigiri? Maybe you’re wondering if you can reheat them.

Onigiri is the perfect on-the-go snack, but they just taste better when eaten warm. Sadly, reheated rice often becomes congealed and dry with an unpleasant chewy texture.

To prevent this, I’ve tried three different reheating methods to determine which one will best revitalize their freshness and flavor.

And when it comes to storing onigiri, you’ll be pleased to hear they keep and freeze super well. So, I’ve included some tips on how to go about this.

A note on my experiment

Last night, I prepared some onigiri but overestimated how hungry I was, so ended up with a few too many.

Lucky for me, this meant I could snack on them again the next day.

Wanting to retain their original savory, salty flavor and moist, sticky texture, I experimented with no less than three different reheating methods.

These included:

Reheating onigiri in the microwave (best method overall)
Reheating onigiri in a frying pan: making yaki onigiri (revamps onigiri with a delicious crunch)
Reheating onigiri in a steamer (good for reheating larger quantities)

I also tried reheating onigiri in the oven, but it wasn’t good. The onigiri turned out dry, chunky, and chewy.

Related: How To Reheat Edamame

Results summary

The microwave method was my favorite method. It was ideal for retaining the moisture and softness of the rice and was also incredibly fast and convenient. Best of all, I could be sure my onigiri was heated all the way through.

That being said, I really liked the reimagined onigiri using the frying pan. Coating them with a bit of soy sauce gave them loads of flavor, and frying them added a nice crunchy outer texture.

Frying is the best way to restore stale onigiri.

While less convenient than the microwave, the steamer method produced good results, keeping the rice soft and warming them evenly. If I was reheating a large quantity of onigiri, this is the technique I would use.

Reheating onigiri in the microwave

First, remove the onigiri’s outer layer of nori (if present). Wrap your onigiri tightly in a sheet of damp paper towel, or, alternatively, sprinkle it with water and place it in a bowl covered with plastic wrap. Microwave on 50% power in 20-second increments until hot. Replace the nori and serve.

Both the paper towel method and the covered bowl method produce soft, flavorful onigiri in less than a minute. You can’t beat the microwave for convenience.

How to reheat onigiri in the microwave:

If present, remove any nori from the onigiri and set aside.
Wrap your onigiri tightly in a damp paper towel* and place it on a microwave-safe plate.
On medium heat (50%), microwave in 20-second increments until hot.
Replace the nori and serve immediately.

*Alternative: in a microwave-safe bowl, sprinkle onigiri with water and cover the bowl with plastic wrap, then follow the rest of the steps above.

Adding moisture using a damp paper towel or sprinkled water ensures that the onigiri doesn’t dry out and keeps them soft.

However, be mindful that they warm quickly, so 20 to 40 seconds should suffice.

Too long in the microwave will leave you with dry onigiri with a chewy texture.

Also, don’t microwave too many onigiri at once. Two would be my limit. After that, they start to heat more unevenly.

If your onigiri has an outer layer of nori, removing it before reheating prevents it from becoming soggy. Instead, it will retain its crispy crunch when you replace it post-reheating.

You can also microwave onigiri securely wrapped in microwave-ready plastic film (and get great results), but not everyone will be comfortable with this. The USDA don’t advise letting plastic wrap touch your food in the microwave.

My verdict

This technique was quick and practical and provided consistently good results in terms of keeping onigiri soft and moist.

A significant perk of the microwave method was that it warmed the onigiri up evenly. No more biting into boiling hot rice and discovering a cold inside!

If you’re in the mood for a warm snack in a hurry, I’d recommend using this method.

Reheating onigiri in a frying pan (making yaki onigiri)

Remove nori if present and set aside. Heat some butter or oil in a pan on medium heat. Fry your onigiri for two minutes on each side. Optionally, brush your onigiri with soy sauce, and fry for a further minute on each side or until a crunchy layer develops. Replace your nori and serve hot.

The result of this is a delicious dish known as yaki onigiri.

It’s the perfect way to revive old onigiri that’s turned stale so wouldn’t be saved by the microwave or steaming.

How to reheat onigiri in a frying pan:

If present, remove any nori from the onigiri and set aside.
On medium heat, warm up some butter or oil.
Fry onigiri for two minutes on each side.
As an optional step, brush your onigiri with soy sauce*.
Fry for a further minute on each side or until a crust develops.
Remove from the heat, replace your nori, and serve hot.

*Soy sauce is traditionally used to develop the crunchy outer layer of yaki onigiri, but you can also use teriyaki sauce or sweet miso, depending on your flavor preference.

I like to use sesame oil when reheating onigiri in a pan, but any soluble fat works, including vegetable oils, bacon grease, and butter.

Be mindful of the temperature of your pan. Too hot, and the onigiri will burn on the outside but remain cold in the center.

Top tip: If you feel your onigiri is too far gone for even yaki onigiri, you can redeem it by making ochazuke. This is a dish comprising rice and tea. (Personally, I enjoy onigiri broken up into piping hot green tea – a delicious, warm, comforting treat.)

My verdict

Making yaki onigiri would be my go-to method if I had a bit of extra time on my hands.

The onigiri was moist and flavorful on the inside and crispy and crunchy on the outside. And you’ll never get bored because you can play with the flavor profiles by brushing the onigiri with different coatings.

Next time I’ll try miso.

Reheating onigiri in a steamer

Set up your steamer. Add water and bring it to a simmer. Remove any nori (if present). Line the steamer basket with perforated baking paper to prevent sticking. Place your onigiri, spread out, in the steamer basket and cover with a lid. Heat them for 4 to 5 minutes. Replace your nori and serve hot.

Steaming onigiri softens the rice and warms them all the way through. It’s an excellent method for reheating a few onigiri at a time.

How to reheat onigiri in a steamer:

Set up your steamer.
Bring water to a simmer.
Remove nori if present and set aside.
Line your steamer basket with perforated baking paper.
Spread your onigiri out in the basket and place over simmering water.
Cover with a lid and heat for 3 to 5 minutes.
Remove them from the basket, replace your nori, and serve hot.

Lining your steamer basket with baking paper prevents your onigiri from sticking to the basket. Spread them out, too, to stop them from attaching to each other.

Make sure you perforate the paper (poke some holes in it) so the steam can still rise effectively.

If you don’t have any baking paper, you can also use cabbage or lettuce leaves.

Check on the onigiri often so you don’t overheat them.

Overheating them will leave you with mushy, soggy rice that isn’t nice to eat.

My verdict

While this method is an excellent alternative to the microwave, it wasn’t as convenient or practical.

In terms of results, though, the onigiri retained its soft stickiness and salty flavors.

The steam penetrated all the way through the rice cakes, warming them evenly.

If you’re reheating onigiri for a few people and have the time, using the steamer technique is a good idea and will be the least fuss.

Can you reheat onigiri in the oven?

You can reheat onigiri in the oven, but I wouldn’t recommend it. The key to good onigiri is soft, sticky, and moist rice. The oven will dry the rice out, so you’ll end up with chewy, dry rice that wants to fall apart (even if you add moisture before heating it).

If you do want to reheat your onigiri in the oven, here’s how:

Set your oven to 300°F (150°C). Remove nori, if present, and set aside. Lightly sprinkle your onigiri with water and wrap it tightly in tin foil. Heat them for five minutes or until warmed through. Remove them from their foil, replace your nori, and serve hot.

How to store onigiri in the fridge

Remove any nori and wrap the onigiri securely in plastic wrap. Optionally, fold a dishcloth over your plastic-wrapped onigiri to keep them cool and safe without exposing them directly to too much cold air. Onigiri can last for up to 3 days in the fridge.

The fridge tends to dry out rice, so it’s essential to cover your onigiri firmly to retain moisture and keep out air.

This way, you won’t end up with stale, hard rice cakes.

Nori will turn soggy in the fridge. For maximum crunch, store nori separately in a moisture-free sandwich bag (with all the air sucked out).

Alternatively, place your nori against the plastic-wrapped onigiri and cover with a second layer of plastic wrap.

Related: How To Store Mochi

How to freeze onigiri

Remove any nori from your onigiri and wrap them tightly in plastic wrap. Place your wrapped onigiri in a freezer or zip-lock bag, removing as much air as possible (I suck it out with a straw). You can store onigiri in the freezer for up to two months.

How to freeze onigiri:

Remove nori (if present).
Wrap them tightly in plastic wrap.
Place wrapped onigiri in a freezer bag.
Remove as much air as possible and seal the bag.

To keep your onigiri as fresh as possible, prioritize minimizing their exposure to air. The tighter the wrap, the less likely air is to enter and dry out your rice.

The double layer of plastic wrap and freezer bag goes a long way to preventing freezer burn.

If you’re opposed to plastic, onigiri can also be stored wrapped in parchment paper.

How to reheat frozen onigiri

Always reheat frozen onigiri straight from the freezer. Never let onigiri thaw naturally. Wrap the frozen onigiri in a damp paper towel and heat it in the microwave in 30 seconds intervals until soft and warm. You can also put the onigiri in a bowl and cover it with plastic wrap.

If you let the onigiri thaw to room temperature on its own, the outer layers of rice will dry out and turn hard, while the inside will turn mushy and horrible.

How long does onigiri last?

To keep your onigiri as tasty and fresh as possible, keep the following guidelines in mind when storing them.

Room temperature: Plain rice onigiri can stand at room temperature for up to six hours (8 hours if stuffed with umeboshi, a natural preservative), but store those with perishable fillings within two hours.
Refrigerated: Onigiri will stay fresh in the fridge for up to three days. Keep onigiri with a mayonnaise-based filling for only one to two days.
Frozen: Onigiri freezes well and will stay fresh for up to two months.

Can you eat onigiri cold?

Onigiri is a popular bento box snack and is sold at convenience stores all over. You can eat them cold, but many prefer heating them or at least letting them warm to room temperature. Cold onigiri sometimes takes on a greasy, congealed texture.