Name: Kombu no Tsukudani (Japanese Sweet-Soy Simmered Kelp)
Prep time: 5 min
Cook time: 30 min
Total time: 35 min
Ingredients: 100 g leftover dashi kombu (rehydrated (about 15 g dry), sliced into 3 mm strips); 2 tbsp sake; 2 tbsp mirin; 1 tbsp sugar; 2 tbsp vinegar (plain grain or rice vinegar); 4 tbsp soy sauce; 1 tbsp honey (added at the end); 2 tsp toasted white sesame seeds

Kombu no tsukudani (昆布の佃煮) is the sticky, sweet-and-savory sibling of shio kombu — the same leftover dashi kelp, cooked down in a soy-sake-mirin glaze with a touch of honey and vinegar until it turns dark, glossy, and unmistakably Japanese. It goes on rice, in onigiri, and over hot green tea for ochazuke.

Where shio kombu is dry and salty, tsukudani is sticky and rich. Both start from the same place: kombu that has already given its umami to a pot of dashi. This is the other useful thing you can do with it.

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A small white cherry-blossom-shaped Japanese dish holding finished kombu no tsukudani — dark glossy strips of kelp with white sesame seeds scattered through — resting on a light wooden table

Why You’ll Love This Recipe

Uses leftover dashi kombu. Same zero-waste starting point as shio kombu, going in a completely different direction.
The ultimate rice topping. A small pile on hot white rice is a full breakfast in Japan.
Stovetop-only. One pan, about 30 minutes, no oven.
Keeps beautifully. Up to two weeks in the fridge — the flavor actually improves after a day or two.

What is Tsukudani?

Tsukudani (佃煮) is a Japanese preservation technique — small ingredients simmered in soy sauce, mirin, and sugar until the liquid is nearly gone and the result is dark, sticky, and shelf-stable. It comes from Tsukudajima, a small island in Edo (now Tokyo) where fisherfolk used to preserve their catch this way.

You can make tsukudani from tiny fish, from nori, from shiitake — but kombu is the most common at home because it uses something you already have. It is intensely flavored; a chopstick’s worth is enough for a bowl of rice.

Shio Kombu vs. Kombu Tsukudani

Both use the same leftover dashi kombu. The difference is what happens next:

Shio kombu — simmered, then oven-dried, then coated in finishing salt. Dry, salty, keeps for weeks at room temperature.
Kombu tsukudani — simmered down until sticky and glossy, finished with honey and sesame. Sweet-savory, refrigerated, keeps 2 weeks.

If you save your dashi kombu in the freezer, do both — they cover completely different uses.

Ingredients

Ingredient	Amount	Notes
Leftover dashi kombu	100 g rehydrated (about 15 g dry)	Sliced into thin strips
Sake	2 tbsp
Mirin	2 tbsp
Sugar	1 tbsp	Regular white sugar is fine
Vinegar	2 tbsp	Plain grain or rice vinegar
Soy sauce	4 tbsp
Honey	1 tbsp	Added at the end for gloss and depth
Toasted sesame seeds	2 tsp	White, for finishing

Like shio kombu, this begins with leftover dashi kombu, simmered in soy sauce and mirin and finished with toasted sesame seeds.

Some recipes include garlic (¼ teaspoon) — I skipped it. The kombu already has plenty of umami and I prefer to taste the kelp cleanly. If you like garlic notes, it works.

How to Make Kombu no Tsukudani

Step 1: Slice and Add to the Pan

Squeeze the softened kombu of excess moisture. Slice it into thin strips — about 3 mm wide and 3–4 cm long — and drop it into a frying pan or shallow saucepan. A wider pan reduces faster.

A wide black non-stick frying pan on an IH cooktop holding thinly sliced strips of rehydrated leftover dashi kombu — the starting point for kombu no tsukudani

Step 2: First Simmer — Without Soy Sauce

This is the key to good kombu tsukudani. Add the sake, mirin, sugar, and vinegar to the pan with the kombu — hold back the soy sauce for now. Adding the soy too early makes the kombu tighten up before it has softened enough.

Sliced kombu strips simmering in a shiny mirin-sake-sugar-vinegar liquid in a black frying pan, with a rubber spatula visible on the right — the first covered simmer stage of kombu no tsukudani

Bring to a gentle boil, then cover with a lid and reduce to medium-low. Simmer for 10–15 minutes, or until the kombu is soft and pliable when you press it with a chopstick.

A pan lid placed on top of the frying pan on the IH cooktop, sealing in the steam as the kombu tsukudani simmers underneath during its first covered stage

Step 3: Add Soy Sauce and Simmer Again

Uncover, pour in the soy sauce, and stir. Put the lid back on and continue to simmer over medium-low heat for another few minutes, letting the kombu drink up the soy. The color will deepen noticeably.

Step 4: Uncover, Add Honey, and Reduce

Take the lid off and add the honey. Turn the heat up slightly and stir often as the remaining liquid cooks away.

A bottle of Japanese Manuka blend pure honey being held over a pan of soy-simmered kombu strips, ready to be squeezed in to finish the tsukudani glaze

Keep stirring until the sauce is nearly gone and the kombu is thickly coated. The mixture will look almost black, glossy, and slightly sticky.

Finished kombu no tsukudani gathered in a mound in the center of the frying pan — dark, glossy, sticky strips of kelp coated in a rich soy glaze with a black spatula pushing it together

Step 5: Finish with Sesame

Turn off the heat. Sprinkle in the toasted white sesame seeds and stir through so they cling evenly.

A generous pinch of toasted white sesame seeds sprinkled over the finished glossy kombu no tsukudani in the pan, ready to be stirred through

Transfer to a clean container to cool. Once cool, keep in the fridge.

Finished kombu no tsukudani served in a small cherry-blossom-shaped white porcelain dish on a wooden table — glossy dark kelp strips scattered with sesame seeds

How to Use Kombu no Tsukudani

Over hot rice. A small mound of tsukudani on a bowl of freshly cooked white rice is a classic Japanese breakfast.
Onigiri filling. A spoonful in the center of a rice ball — a beloved combination alongside other classic onigiri fillings.
Ochazuke. Put hot cooked rice in a bowl, top with a spoonful of tsukudani, and pour hot green tea (or dashi) over the top. Two-minute comfort food.
Bento box side. Sits in one corner of a bento — no reheating needed, salty enough to season the rice.
Cold tofu topping. A small pile on chilled silken tofu with a splash of soy sauce.

Storing

Kombu tsukudani keeps well because of the high sugar and soy content. Store in a clean sealed container in the fridge for up to 2 weeks. The flavor deepens after a day or two. It also freezes well — portion into small containers and freeze up to 2 months.

Frequently Asked Questions

What is tsukudani?

Tsukudani (佃煮) is anything simmered slowly in soy sauce, mirin, and sugar until the liquid is almost gone and the result is dark, glossy, and strongly seasoned. Kombu, small fish, clams, and mushrooms are all common. It’s designed to keep and to be eaten in small amounts with rice.

Why simmer without soy sauce first?

Kombu needs to soften before it takes on salt. Simmering it in water and vinegar first breaks it down; adding soy sauce too early tightens the kelp and it stays tough no matter how long you cook it.

How long does kombu tsukudani keep?

About two weeks in the fridge in a sealed container, and it freezes for a couple of months. The sugar and soy sauce act as preservatives — that’s what tsukudani was invented for, long before refrigeration.

How do you eat it?

A small mound on top of hot white rice is the standard way, and a little goes a long way. It’s also good in onigiri, folded into ochazuke, or served as one of several small dishes with a Japanese breakfast.

Can I use fresh kombu instead of spent dashi kombu?

Yes, but it’s wasteful — fresh kombu is expensive and its best quality is the dashi it gives up. Using kombu that’s already made your soup stock is both cheaper and the traditional practice.

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