Onigiri (おにぎり) - Japanese Rice Balls
Onigiri (おにぎり), which are sometimes called Omusubi (おむすび), are Japanese rice balls that come in a variety of shapes and sizes. They can be filled or unfilled, but the idea is that they're a seasoned and ready-to-eat bowl of rice that you can pick up and eat with your hands. They've become an iconic part of bento box lunches because of their portable nature, and the rice balls are often shaped and decorated to make different characters.
Why This Recipe Works?
- Using Japanese short-grain rice is the key to tender onigiri even after the rice balls have cooled to room temperature.
- Using freshly cooked rice that's just cool enough to handle is the key to getting a nice shape without compacting it too much as the rice is pliable, and the high temperature will discourage you from squeezing it too much.
- By wetting and salting your hands, it not only keeps the rice from sticking to them, but it also applies an even layer of seasoning to the outside of the rice balls.
- Eating onigiri should be like eating a fluffy bowl of freshly cooked rice, not a dense brick of cold dough, that's why it's important not to compress the rice too much when you shape it.
What Rice to Use
Making good onigiri is mostly about the rice, how it's cooked, and how it's shaped, so it's essential to start with a type of rice that's well suited for making rice balls. First, it helps to understand that rice contains starch, and starch consists of amylose and amylopectin.
Different cultivars of rice have different ratios of starch, but the length of each grain is usually a good indicator of which way the ratio swings. The shorter the grain, the more amylopectin they typically hold, and the longer the grain, the more amylose.
Amylose likes to form linear bonds, while amylopectin forms branched bonds. When rice is cooked in water, the starch's crystalline structure is broken, and the molecules hydrate to form a gel. Hydrated amylopectin is more gooey and sticky than hydrated amylose, which is why short-grain rice has a stickier texture than medium or long-grain rice.
As the rice cools, the starch molecules retrograde and rearrange themselves back into a crystalline structure. This is what makes leftover rice hard and "dry." Amylopectin retrogrades much slower than amylose, which is why rice that has a high ratio of amylopectin to amylose tends to take much longer to go stale. This is why it's important to use rice with a high proportion of amylopectin when making onigiri.
When buying rice, check the packaging to confirm it says "short-grain rice." Many Japanese-American brands of rice are actually a medium-grain cultivar called Calrose, and this is not ideal. Some common cultivars of short-grain rice include Koshihikari, Tamanishiki, and Milky Queen.
September and October are the regular seasons for harvesting rice, and fresh rice (usually labeled Shinmai or New Crop Rice) has a better texture and flavor than older rice. Fresh rice tends to have a higher moisture content, so if you're able to find some, be sure to reduce the amount of water you use slightly when you cook it.
Other Ingredients for Onigiri
- Filling - Onigiri can be filled with a variety of salty low-moisture foods. Traditional fillings include umeboshi (salted plum), salted salmon, seasoned katsuobushi (dried skipjack tuna flakes), and tarako (cod roe). For a more detailed list of fillings, see the section below.
- Salt - Although onigiri fillings tend to be very salty, there's only a small amount in the very center, so your onigiri will taste much better if you salt the outside of the rice ball. I generally use a good quality sea salt that's not too coarse.
- Wrapper - The wrapper has a few practical purposes. First, it makes it easy to pick the Onigiri up with your hands without getting rice stuck to them. The second thing is that it holds the rice together, so it doesn't crumble apart and fall in your lap while eating it. Whether you're using nori or some kind of leaf, the wrapper also imparts flavor while making the white rice more visually interesting. Another style of onigiri, called Nikumaki Onigiri wraps the whole rice ball in a thin sheet of meat before glazing it with teriyaki sauce.
Types of Onigiri
Onigiri has a history dating back over 2000 years in Japan, so there's a fair amount of variation in how they're made, but I've listed some of the most popular ones by filling below:
- Shio - Shio literally means "salt," and shio onigiri is made with only salt on the outside and no filling inside.
- Umeboshi - Ume is a type of Japanese apricot that is salted and partially dried to make a very salty and sour pickle called umeboshi. The bright red ones are pickled together with red shiso leaves, which gives them their vibrant magenta hue. The high concentration of salt and acidity makes these well suited as a filling for rice balls.
- Okaka - The name sounds awful, but okaka is a mixture of katsuobushi (smoked, dried, and shaved skipjack tuna) and soy sauce. It's packed with umami and makes for a delicious filling for onigiri.
- Salted Salmon - Salmon was traditionally salted as a way to preserve it, and this salted salmon can be grilled and flaked to make a tasty and colorful filling for onigiri. To make this at home, you can simply cover a salmon fillet on all sides with a generous amount of salt and set it on a rack over a tray in the fridge to salt and drain overnight. Then you can remove the excess salt and grill it in a toaster oven or in a frying pan until it's well done.
- Tarako - Tarako refers to salted cod roe, and mentaiko is a salted cod roe that's been seasoned with chili peppers. These are both used raw as a filling for onigiri, but if you aren't eating the rice balls right away, I recommend grilling the roe to fully cook it before you stuff it into the rice.
- Konbu - Konbu is a type of kelp that can be thinly sliced and cooked with a mixture of soy sauce, mirin, and sake to make a flavorful condiment called tsukudani. This can be stuffed inside of an onigiri. Another preparation for konbu is to slice freshly harvested konbu into thin strips before salting and drying it. This is known as shio konbu, and it's also used as a filling for rice balls.
- Tuna Mayo - Although it wasn't popularized until 7-Eleven started selling it in 1983, Tuna Mayo is now said to be the most popular filling for onigiri in Japan. It's made by mixing canned tuna with Japanese-style mayonnaise and soy sauce. You can get the recipe for my Tuna Mayo Onigiri at the link above.
- Tenmusu - Tenmusu is short for Tempura Omusubi, which is an alternate name of Onigiri. It's typically stuffed with a piece of shrimp tempura that has been soaked in a sweet and savory sauce.
- Karaage - Karaage or Japanese fried chicken, is another popular filling for onigiri.
- Spam Musubi - I threw this in the list because it's a descendant of Japanese rice balls, but Spam musubi was created in Hawaii and is made by topping a rice ball with teriyaki glazed spam and wrapping it with nori.
Other Styles of Onigiri
- Mazé gohan - Mazé gohan literally means mixed rice, and it's made by mixing in various ingredients such as pickles or furikake into cooked rice to season it.
- Gomoku - Gomoku gohan is a type of Japanese pilaf made by cooking rice with vegetables, mushrooms, meat, or seafood seasoned with dashi, soy sauce, and sake. This can then be used to make rice balls. Gomoku onigiri typically isn't wrapped with nori.
- Yaki Onigiri - Yaki Onigiri literally means grilled onigiri, and they were traditionally made by grilling rice balls over charcoal and basting them in a sweet and savory glaze. The high temperature crisps the exterior surface of the rice while giving it a wonderful toasty aroma. These days, most people make yaki onigiri in a frying pan, and I love finishing mine with a pat of butter and splash of soy sauce.
Rice Ball Shapes
Although "onigiri" is usually translated to "rice ball," they're most commonly triangular. Still, onigiri comes in many shapes and sizes, and here are a few of the more common ones:
- Triangle - This is the most orthodox shape for onigiri, and I suspect it has to do with the fact that this shape is relatively easy to achieve with your hands.
- Tawara - Tawara is a cylindrical bale of rice. Tawara-shaped onigiri are small cylinders of rice, which make them easier to pack into bento boxes.
- Round - In the Tōhoku region of Japan, onigiri are circular in shape.
- Other - these days, there are onigiri molds in many shapes and sizes so you can make anything from a heart-shaped onigiri to a flower-shaped onigiri.
How to Make Onigiri
Rinse the rice and then cook it in the rice cooker as you normally would. If you are using fresh rice, be sure to reduce the amount of water slightly to account for the higher moisture content. If you don't have a rice cooker, I have a detailed tutorial on preparing rice on the stove in my sushi rice recipe, so be sure to check that out.
While the rice is cooking, prepare your filling(s) and wrapper(s). If you are using umeboshi, you should remove the pit to make it easier to eat. For nori, you'll want to cut each sheet into thirds the long way. You can do this with a clean set of kitchen scissors, or if the nori is fresh, you should be able to just crease and tear it with your hands. You'll also need to prepare a bowl of water for dipping your hands in and a small bowl of salt to season the onigiri.
Once the rice is done steaming, use a wet spatula or rice paddle to mix and fluff it. It's best to use a cutting and folding motion to do this, but be sure to gently do it, so you don't smash the rice's individual grains.
Then you'll want to transfer the rice to a bowl to get it to cool down a little faster. The goal here is to lower the temperature enough so that you can handle the rice without burning yourself, but it should still be hot. Be sure to keep the bowl of rice covered with a damp towel at all times to prevent the rice from drying out.
Once the rice has cooled enough to handle, wet your hands in the water bowl and then dab your index finger in the bowl of salt. Some of this will season the rice's exterior, so you want a fairly good amount of salt on your finger. Rub this between your hands to distribute it evenly.
Cup your non-dominant hand and scoop about one-sixth of the rice into a mound that's centered between your palm and fingers. Press one pitted umeboshi into the center of the rice and then use the surrounding rice to bury it.
Now you want to curl your palm and fingers straight up like you're trying to make your hand look like a taco.
Bend your index and middle finger towards your palm to make an upside-down "v" with your other hand. Use this hand to shape the mound of rice in your taco-shaped hand into a triangle. You want to gently squeeze the rice, so it sticks together, but don't smash it together.
Roll the rice ball onto another side in your taco-shaped hand, and then shape it again with your other hand. Repeat this process until you have an equilateral triangle.
To wrap your onigiri, place a strip of nori centered on the triangle's tip and then wrap each side around the rice ball and tuck the flaps under the bottom.
Onigiri (おにぎり) literally means to shape or grip with your hands, and it refers to the method of preparation. The name is similar to nigiri sushi because both are prepared by shaping the rice with your hands, but these are two different dishes. Onigiri can be made with various mix-ins, fillings, and wrappers and come in many shapes and sizes, but the one thing they all have in common is that they are made to be easily eaten with your hands.
O-ni-gi-ri is a five-syllable word, and each one is pronounced as follows:
o - like order
ni - niece
gi - ghee
ri - real the "ri" sound does not exist in the English language and is like an "r" pronounced at the front of the mouth like an English "l".
Depending on the filling, onigiri can be made plant-based.
Sushi is always made with rice that has been mixed with vinegar, salt, and sugar. Onigiri can be made with either seasoned or plain rice, but the rice is never vinegared.
Technically Omusubi has to be a triangle in shape as it is supposed to be the shape of a mountain, while Onigiri can be any shape. That being said, the terms are often used these days interchangeably. Omusubi is the more common name in the west of Japan, while Onigiri is the dominant name in eastern Japan.
It's possible, but I don't recommend it as the bran makes it challenging to get the rice to stick together properly without mashing the rice up. This involves cooking the rice with too much water to get the rice kernel to swell out of the bran. Then you'll need to use some force to press the rice together. If you can find it, I recommend using partially milled rice instead. This is partially brown rice that's had most of the bran milled off but retains the germ, which is where most of the nutrients are.
- 1 ½ cups Japanese short-grain rice (2 rice cooker cups)
- 1 ⅔ cup cold water
- 6 whole umeboshi
- 2 sheets Unseasoned nori
- Wash and cook the rice in a rice cooker as you normally would, or if you are doing it on the stove, you can follow the instructions on my sushi rice recipe (but be sure to use the amount of rice and water specified above).
- While you're waiting for the rice to cook and steam, remove the pits from the umeboshi.
- Cut the sheets of nori into thirds by either using scissors or creasing and tearing the nori.
- Prepare a medium bowl of water and a small bowl of salt.
- When the rice is done, fluff it with a spatula and transfer it to a bowl to cool. Keep the bowl covered with a damp towel to keep the rice from drying out.
- When the rice has cooled enough to handle without burning yourself, wet your hands in the bowl of water and dip your index finger into the bowl of salt.
- Rub the salt into both hands and then scoop ⅙ of the rice into one hand. Press one pitted umeboshi into the center of the mound of rice and cover it with the surrounding rice.
- Curl your fingers up and over the rice, and then use your index and middle fingers on your free hand to shape the rice into a triangle, but do not over squeeze the rice.
- Roll the rice ball on your hand onto another side and repeat until the triangle has equal length sides, and it's roughly the same thickness.
- To wrap the onigiri, place a strip of nori centered on the rice and then wrap each side of the nori around the triangle and under the base.
- Garnish the top of the onigiri with a little dab of umeboshi so you can identify what's inside.
Hi Marc, thanks for the recipe! Can I use precooked frozen short-grain rice that is warmed up for the nikumaki?
Marc Matsumoto says
You're welcome June! It's not ideal because the starch in frozen rice is retrograded so it won't be quite as sticky as freshly cooked rice (even if you warm it up). It will make it harder to wrap. That being said, you can certainly try it out and worst case scenario just turn it into beef fried rice 😉