Kombu tsukudani is a traditional Japanese simmered side dish made with kelp, soy sauce, and sweetener. Kombu is cooked until tender and has an umami-rich, sweet, savory flavor and a glossy finish. It's perfect for enjoying over steamed rice in a Japanese-style breakfast or onigiri. This is a low-waste way to reuse kombu after making dashi.
When I was working at a plant-based cooking school, one of the most common questions from students was "what to do with kombu after making dashi?"
My coworker, who was a huge kombu lover, said she just nibbles on it or bakes it crispy for snacking. But unseasoned kombu is not really my thing. Instead, I make kombu tsukudani!
I think of tsukudani as a Japanese savory jam. Kombu is cooked down with soy sauce and sugar until tender and glossy. Instead of spreading it on a piece of toast like fruit jam, it's often enjoyed over plain steamed rice to enjoy its umami-rich, sweet, and savory flavor.
Serve it with steamed rice, miso soup, and grilled salmon to create your own Japanese-style breakfast!
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What Is Kombu Tsukudani?
Kombu tsukudani, or kombu no tsukudani (昆布の佃煮), is a traditional Japanese simmered kelp side dish usually enjoyed over rice. Kombu is a type of kelp often used to make dashi, a Japanese broth. Kombu is simmered until tender and seasoned with soy sauce, sake, mirin, and sweetener. As a result, it has an umami-rich, sweet-savory flavor with a glossy finish that pairs perfectly with a bowl of hot steamed rice.
Kombu tsukudani is a low-waste way to use leftover kombu after making dashi. Instead of discarding dashi kombu after use, turn it into a delicious side dish.
If you're new to kombu, check out my kombu kelp guide to learn the basics!
Why You'll Love This Recipe
- Low-waste cooking: This recipe turns leftover kombu from making dashi into a savory-sweet side dish instead of throwing it away.
- Perfect rice companion: Kombu tsukudani has a concentrated umami flavor that pairs so well with plain steamed rice. It's also great for ochazuke, bento, or a Japanese-style breakfast.
- Naturally simple: You only need a few Japanese pantry staples like soy sauce, sake, mirin, and maple syrup to make a glossy, flavorful rice topping.
- Great onigiri filling: The sweet-savory flavor makes it a classic filling for kombu onigiri. It's a humble yet satisfying way to enjoy onigiri.
Ingredients You'll Need
- Kombu: you'll need hydrated kombu for this recipe, not dried. If you only have dried kombu, it needs soaking first. For this reason, I recommend using leftover kombu from making dashi. It's too tedious to make tsukudani every single time I make dashi. So I cut it thinly and freeze each batch of kombu. Once I have enough, I use it to make kombu tsukudani!
- Rice vinegar: Kombu is tough seaweed and needs longer cooking time to soften. But adding vinegar makes the tenderizing process faster. A few tablespoons of vinegar are enough to do the magic, and you won't even taste the acidity after cooking.
- Maple syrup: Tsukudani is commonly made with sugar, but I like mine with maple syrup. It adds complex flavor and gentle sweetness that pairs beautifully with soy sauce. You can also substitute with granulated sugar, brown sugar, or honey.
- Soy sauce: main savory/salty flavor.
- Sake and mirin: add depth and sweetness.
- Sesame seeds: optional. They add a really nice nutty flavor and texture.
Can I Use Dried Kombu Instead of Leftover Kombu?
Yes, but it needs soaking first to cut and shorten the cooking time.
If you're making kombu tsukudani with dried kombu, soak the kombu in 2 cups of water for 30 minutes. Then remove the kombu from the water and slice it thinly. Do not discard the water! It's umami-rich cold-brew kombu dashi, so you can use it to make tsukudani.
Leftover dashi kombu is already softened, so it is easier to make tsukudani.
How to Make Kombu Tsukudani
- Slice kombu into 1-inch-long, thin strips. If your kombu is wide, cut it into 1-inch-wide pieces first, then slice thinly. Cut across the fibers, not along them, to help the kombu tenderize faster.
- In a pot, combine kombu strips, water, and vinegar. Bring to a gentle boil over medium heat and cook until the kombu is tender and most of the liquid has reduced, about 30 minutes. Add a splash of water and continue cooking if it's not tender enough.
Cooking time may vary depending on the type of kombu and thickness. Kombu is ready for the next step when:
- Kombu is a little more tender than you want the finished tsukudani to be.
- Most of the liquid has reduced.
- Stir in soy sauce, sake, mirin, and maple syrup. Stir occasionally and continue cooking until the sauce thickens and almost no liquid is left, for 10-15 minutes. When it is almost done, stir in sesame seeds.
Tip: Once seasonings are added, kombu can become harder to soften further and may firm up slightly as it cooks down. Make sure the kombu is a little more tender than you want the finished tsukudani to be before adding the seasonings.
Tips for the Best Kombu Tsukudani
- Use leftover dashi kombu: kombu used to make dashi is already hydrated and softened, a great head start for a tender texture.
- Slice kombu thinly: cutting kombu thinly across the fiber helps tenderize the kombu. The fibers usually run lengthwise, so cutting across them makes the strips easier to tenderize.
- Cook kombu more tender than you think before adding seasonings: Kombu can firm up after adding seasonings. So it's important to cook kombu with vinegar until extra tender before adding any seasonings.
- Adjust the cooking time: Cooking time may vary depending on the type and toughness of kombu you use. Add more water and continue cooking if it's not tender enough.
- Reduce until glossy: The tsukudani is done when the sauce is thick, glossy, and almost no liquid is left. It should look coated, not soupy.
How to Serve Kombu Tsukudani
Since kombu tsukudani has a concentrated flavor, it is meant to be enjoyed with plain rice! You only need a small amount for a bowl of rice as a topping. It can be a part of a balanced Japanese-style meal.
Ichiju Sansai principle comes in handy when putting together a Japanese meal. Ichiju Sansai is a traditional Japanese meal structure consisting of rice, soup, a main dish, and two sides.
Here are some ideas to serve with a kombu tsukudani meal:
- Rice: A bowl of plain rice is great! Kombu tsukudani is also great for kombu onigiri filling.
- Soup: Kabocha Squash Miso Soup and Shio Koji Tomato Soup.
- Main Dishes: Air Fryer Karaage, Nikujaga (Meat and Potato Stew), Shio Koji Salmon, and Shio Koji Chicken.
- Side Dishes: Japanese Sunomono Cucumber Salad, green salad with Japanese Sesame Dressing, Cold Soba Noodle Salad, and Tamagoyaki (Japanese rolled egg omelette).
How to Store Kombu Tsukudani
Let the kombu tsukudani cool completely, then transfer it to an airtight container and store it in the refrigerator.
Use a clean spoon or chopsticks each time you take some out, so it keeps better. If you make a larger batch, you can also freeze it in small portions.
Because this recipe uses leftover kombu and homemade seasoning, the exact storage time can vary. I recommend enjoying it within 3-4 days for the best texture and flavor.
I found that kombu tsukudani feels slightly firmer when chilled in the refrigerator. But when served on hot steamed rice, the texture feels softer and revived.
More Japanese Recipes
Cooking Japanese meals is so easy, so here are more recipes you can try at home!
- Tuna Mayo Rice Balls
- Chirashizushi (Scattered Sushi)
- Natto Maki
- Tamago Sando
- Fruit Sando
- How to Make Shio Koji
- How to Make Shoyu Koji
Kombu Tsukudani
Ingredients
- 3 oz hydrated kombu I recommend using leftover kombu from making dashi
- 2 cups water
- 1½ Tablespoons rice vinegar
- ¼ cup soy sauce
- ¼ cup sake
- ¼ cup mirin
- 2 Tablespoons maple syrup
- 1 teaspoon sesame seeds
Instructions
- Slice kombu into 1-inch-long, thin strips. If your kombu is wide, cut it into 1-inch-wide pieces first, then slice thinly. Cut across the fibers, not along them, to help the kombu tenderize faster.
- In a pot, combine kombu strips, water, and vinegar. Bring to a gentle boil over medium heat and cook until the kombu is tender and most of the liquid has reduced, about 30 minutes. Cooking time may vary depending on the type of kombu and thickness.
- If the kombu is not tender enough, add a splash of water and continue cooking. Tip: Once seasonings are added, kombu can become harder to soften further and may firm up slightly as it cooks down. Make sure the kombu is a little more tender than you want the finished tsukudani to be before adding the seasonings.
- Stir in the soy sauce, sake, mirin, and maple syrup. Stir occasionally and continue cooking until the sauce thickens and almost no liquid is left, about 10-15 minutes. When it is almost done, stir in sesame seeds.
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