Onigiri Fillings: Classics and New Ideas with Amounts

Basic amounts for 6 onigiri

• Rice: 300 g Japanese short-grain rice (2 rice cooker cups), cooked about 600 to 650 g. This gives six onigiri of around 100 g each.
• Salt: about 1 tsp for your palms.
• Nori: 2 sheets, each cut into three strips.
• Filling: 1 to 1 1/2 tbsp per onigiri.

Cook the rice as for sushi, but without vinegar. Read the guide How to Cook Rice for that. It can be shaped as long as it is still warm. The basic recipe with step-by-step instructions is under Onigiri with Tuna and Furikake.

Classic fillings

Umeboshi

The salted, pickled ume fruits taste intensely sour and salty. For 6 onigiri, take 3 large or 6 small umeboshi, remove the pits and tear the flesh into pieces. Half a piece per rice ball is enough, or the acidity covers everything else. If the fruit is too strong for you, stir the paste with a few bonito flakes or use Ume-Dare instead, a milder sauce made from umeboshi.

Salmon (shake or sake)

Rub a 150 g salmon fillet with 1 tsp salt, let it sit for 20 minutes, pat it dry and grill or pan-fry it for 4 to 5 minutes per side. Then remove the skin and bones and flake the meat with a fork. The flakes keep for two days in the fridge. For a sweeter variant, use leftovers of Teriyaki Salmon.

Tuna mayo

The most popular filling in Japanese supermarkets: mix 1 can of tuna (about 130 g drained) with 2 to 3 tbsp Japanese mayonnaise and 1 tsp soy sauce. Squeeze the tuna out well first, or the filling softens the rice. You can whisk Japanese Mayonnaise yourself, and it tastes tangier and more yolk-forward than Western mayo.

Kombu

Kombu tsukudani is seaweed that you cut into strips and cook down in soy sauce, mirin and sugar until soft and glossy. The filling uses up kombu that you have already simmered for dashi. 10 g of dried kombu makes about 4 tbsp, enough for 6 onigiri. Kombu contains a lot of iodine, with more under Kombu.

Okaka

Okaka is the quickest filling: mix 5 g bonito flakes with 1 to 2 tsp soy sauce until they stick together. A dash of mirin rounds it out. Background on the ingredient is under Bonito Flakes.

Modern fillings

In Japan, every konbini has new kinds next to the classics. These variants work with ingredients from regular supermarkets and the Asian grocery store. All amounts are for 6 onigiri.

• Teriyaki chicken: 150 g Teriyaki Chicken, finely diced, with 1 tbsp of the glaze.
• Karaage: 6 small pieces of Karaage, one per onigiri, with half sticking out at the top.
• Tamagoyaki: half a Tamagoyaki made from 3 eggs, cut into 2 cm cubes.
• Kimchi tuna: 1 can of tuna with 3 tbsp chopped Kimchi and 1 tbsp mayonnaise.
• Miso mushrooms: Fry 150 g finely diced shiitake or button mushrooms with 1 tbsp miso, 1 tsp mirin and a little oil in a pan until the liquid evaporates. Vegan if you use vegan miso.
• Edamame and sesame: 100 g shelled edamame and 1 tbsp toasted sesame mixed straight into the rice, with a pinch of salt.
• Seasoning paste: one teaspoon of Shichimi Miso per onigiri for a spicy version.

The Korean counterpart is called Jumeokbap. There you mix the ingredients straight into the rice and shape balls.

Yaki onigiri do without filling: shape the rice balls a bit flatter, pan-fry them on both sides in a little oil and brush them with soy sauce at the end until a brown, crisp crust forms. You need three to four minutes per side. This variant also works with day-old rice, which you warm briefly in the microwave first.

Shaping filled onigiri

1. Set out a bowl of water and the salt. Wet your hands and rub a pinch of salt on your palms.
2. Take about 100 g of warm rice in your hand and press it flat. Press a hollow into the middle with your thumb.
3. Put 1 to 1 1/2 tbsp filling in the hollow and cover it with a little rice.
4. Shape your hands into a roof and press the rice into a triangle with three to four turns. Firm enough to hold, loose enough that the grains aren't crushed.
5. Wrap a strip of nori around the bottom only shortly before eating, and it stays crisp.

Without practice, a plastic onigiri mold or plastic wrap helps: put rice on it, filling in the middle, twist the wrap together and press the ball into shape.

Common mistakes

• Wrong rice: Basmati or jasmine rice isn't sticky enough. Use Japanese short-grain rice or sushi rice.
• Too much filling: More than 1 1/2 tbsp pushes out at the sides.
• Wet filling: Mayo, sauce or marinade soften the rice. Drain well.
• Cold rice: Straight from the fridge it falls apart while shaping.

Shelf life and allergens

Eat onigiri best on the same day. Keep fillings with mayonnaise, egg or fish cool until eating, and for a lunch box pack an ice pack. In the fridge the rice turns hard. Five minutes at room temperature or 20 seconds in the microwave makes it soft again.

Depending on the filling, onigiri contain fish, egg, soy, gluten from the soy sauce and sesame. Umeboshi and kombu are vegan if the soy sauce has no additives.