Kombu Onigiri is a classic Japanese rice ball filled with kombu tsukudani. Kombu is simmered with soy sauce and sweetener to create an umami-rich, sweet-savory tsukudani that complements the plain rice and nori beautifully.
What I love about kombu tsukudani is that it's so versatile! It can be a simple rice topping, onigiri filling, ochazuke, or stir-fry. You can also make so many flavor variations with additions like cheese, ume, or shiso.
One time I posted an onigiri recipe with kombu tsukudani and cream cheese on my Instagram, and people loved it! While simple kombu onigiri is humble and grounding, it's easy to make it richer and more fun by combining kombu tsukudani with cream cheese.
This recipe is part of my Japanese konbini from scratch series, where I recreate my Japanese convenience store favorites at home, including: Tuna Mayo Onigiri, Fruit Sando, Tamago Sando, and Natto Maki. Kombu onigiri is a classic onigiri flavor you can often find at Japanese konbini. Even as new flavors come and go, kombu onigiri remains one of those familiar, comforting options.
Jump to:
What Is Kombu Onigiri?
Kombu Onigiri is a classic Japanese rice ball filled with kombu tsukudani and often wrapped with nori. Kombu (昆布) means kelp, and onigiri (おにぎり) means rice balls in Japanese.
Kombu tsukudani is a seasoned kombu filling. It's made by simmering kombu until tender, then seasoning it with soy sauce, sake, mirin, and sweetener to create a sweet-savory flavor with a glossy finish. Its umami-rich flavor beautifully complements rice and nori.
Homemade kombu tsukudani is a great way to reuse leftover kombu from making dashi, Japanese broth.
Onigiri is a simple and humble meal, but it's packed with flavor. Great for an easy breakfast, portable lunch, or packing it with karaage and tamagoyaki to create your picnic bento!
Why You'll Love This Recipe
- Packed with homemade kombu tsukudani for rich savory flavor, gentle sweetness, and umami.
- A low-waste way to convert leftover dashi kombu into another meal.
- Onigiri is an easy, portable way to enjoy rice with a rich filling.
- Great for a simple breakfast, an easy lunch, or packing to go.
Ingredients You'll Need
- Kombu Tsukudani: Homemade tsukudani is so easy and flavorful! If you have some leftover kombu from making kombu dashi, this is a great way to reuse it. Store-bought tsukudani also works well.
- Cooked Rice: Freshly cooked warm Japanese short-grain rice works best. If you only have leftover rice, warm the rice before use and cool it slightly until you can touch it. You can use white ruce ot brown rice is also delicious.
- Nori: Crisp nori is so satisfying! I usually cut a sheet into 3 strips for a cute wrapping style like the ones in the image. But half a sheet also works well.
How to Cook Rice for Onigiri
For 400g cooked rice, cook about 200g uncooked Japanese short-grain rice, or about 1⅓ rice cooker cups. Freshly cooked warm rice works best for shaping onigiri. I usually cook 2 rice cooker cups and freeze the leftover rice.
Add water equal to 1 to 1.2 times the amount of rice in volume, depending on your preferred texture. Firmer rice works better in onigiri, so I use 5-10% less water than usual. If using a rice cooker, add water about 2mm below the rice cooker water line.
- Rinse the rice several times under cold water until the water runs mostly clear. Soak for 30 minutes to 1 hour, until the grains are opaque.
- Cook the rice according to your rice cooker instructions or preferred stovetop method (see below).
- Gently fluff the rice. Let the rice cool slightly until warm but still easy to handle. Freshly cooked warm rice shapes best for onigiri.
Rice Cooking Method with Pot on Stovetop
When I cook rice in a pot, I use 1 US measuring cup instead of a rice cooker cup. 1 US measuring cup of rice is about 200g. Then add 220ml of water for firm rice for onigiri.
- Rinse the rice several times under cold water until the water runs mostly clear. Soak for 30 minutes to 1 hour until grains are opaque.
- Drain the rice well and add it to a heavy-bottomed pot. Add water.
- Cover with a lid and bring it to a boil over medium heat. When the steam starts to escape from the pot, reduce the heat to low and cook for 10 minutes.
- Remove from heat and let sit for another 10 minutes to steam with the lid on.
- After steaming, use a wet spatula to fluff the rice, flipping the rice from the bottom to even out the moisture.
Troubleshooting note: If you're not sure whether the rice is cooked, you can remove the lid, check if all the water is absorbed, and taste the doneness. If there's still water, cover and cook longer. If the rice is still hard, add a splash of water and cook longer. If the rice is done, cover with a lid, then cook over medium heat for 10 seconds to create a steamy environment in the pot. Then let it sit for 10 minutes.
How to Make Kombu Onigiri
How to Shape Onigiri
- Wet your hands with water to prevent sticking, then lightly sprinkle your palms with salt.
- Scoop about ½ cup (100g) of warm rice into one hand.
- Gently flatten the rice and add about 1-2 tablespoons of kombu tsukudani in the center.
- Wrap the filling with rice. Make a U-shape with your bottom hand and a V-shape with your top hand, and shape it into a triangle by gently squeezing and rotating the onigiri between your hands. Try not to squeeze too hard so the rice stays soft and fluffy.
How to Wrap Onigiri with Nori
- Cut each nori sheet into 3 long strips.
- Place the nori on the work surface with the shiny side down.
- Place the onigiri in the center.
- Bring the ends of the nori to the center to wrap.
- Tack the nori to the bottom.
How to Serve Kombu Onigiri
Kombu onigiri is great for breakfast, lunch, a snack, or a bento. Since the kombu tsukudani is already full of umami-rich, sweet-savory flavor, you don't need much else.
To make it a full meal, try serving it with these Japanese recipes:
- Soup: Kabocha Squash Miso Soup.
- Main Dishes: Air Fryer Karaage, Nikujaga (Meat and Potato Stew), Shio Koji Salmon, or Shio Koji Chicken.
- Side Dishes: Japanese Sunomono Cucumber Salad, green salad with Japanese Sesame Dressing, or Tamagoyaki (Japanese rolled egg omelette).
You can also make a richer variation by adding cream cheese to the kombu tsukudani. The salty-sweet kombu and creamy cheese are such a satisfying combination.
How to Store and Pack Kombu Onigiri
Kombu onigiri tastes best the day it is made, while the rice is still soft and the nori is crisp.
If you are packing it for lunch, let it cool and wrap each onigiri tightly in plastic wrap or parchment paper so the rice does not dry out. Keep the nori separate and wrap it right before eating if you want it crisp.
I don't recommend refrigerating onigiri if you can avoid it because the rice becomes firm and dry. If you need to refrigerate it for food safety, wrap it tightly and gently warm it without the nori before enjoying.
If you're not eating it the same day, I highly recommend freezing. When freezing, wrap onigiri without nori tightly in plastic wrap and keep it in a freezer bag. When ready to enjoy, microwave until warm.
For make-ahead, you can prepare the kombu tsukudani in advance and keep it in the refrigerator. Then make the onigiri fresh when you are ready to eat.
More Japanese Rice and Onigiri Recipes
Love onigiri? Try more Japanese recipes!
- Tuna Mayo Onigiri
- Natto Maki Sushi Rolls
- How to Eat Natto
- Ehomaki Sushi Roll
- Chirashizushi Recipe (Scattered Sushi)
- Sushi Burrito
Kombu Onigiri
Ingredients
- 4 servings kombu tsukudani about ⅔ cup
- 400 g cooked Japanese short-grain rice white or brown rice, see note
- 4 nori strips about ⅓ sheet each
- Sea salt
Instructions
- Wet your hands with water to prevent sticking, then lightly sprinkle your palms with salt.
- Scoop about ½ cup (100g) of warm rice into one hand.
- Gently flatten the rice and add about 1-2 tablespoons of kombu tsukudani in the center.
- Wrap the filling with rice. Make a U-shape with your bottom hand and a V-shape with your top hand, and shape it into a triangle by gently squeezing and rotating the onigiri between your hands. Try not to squeeze too hard so the rice stays soft and fluffy. Repeat with the remaining rice and filling.
- Wrap each rice ball with a strip of nori. Enjoy immediately for crisp nori, or pack to go. (Optional) Add more kombu tsukudani on top of the onigiri for a fancy onigiri shop look.
Notes
Nutrition
For more recipes and updates, follow me on Instagram or TikTok!
If you enjoy the recipe, please leave a comment and ⭐️⭐️⭐️⭐️⭐️! I'd love to know what you think!
Leave a Reply