Wondering what to do with leftover kombu from your Japanese recipes? Make delicious simmered Kombu Tsukudani cooked in a sweet and savory sauce. My tender seasoned kelp recipe is an easy and tasty side dish for your plain steamed rice or onigiri!

Once you start making Japanese dishes, you will realize you are left with a lot of used kombu from making homemade dashi (Japanese soup stock), mentsuyu (noodle soup base), or ponzu sauce. You may wonder what to do with the spent kombu.
Don’t throw those leftover kombu pieces away! You can repurpose them into a delicious simmered kombu dish called Kombu Tsukudani. Follow my recipe and tips below to make this easy and tasty side dish.
Table of Contents
What is Tsukudani?
Tsukudani (佃煮) is a preparation where an ingredient is simmered for a long time in a sweet and savory sauce (typically made from soy sauce, sugar, and mirin). It usually has an intensely sweet and savory flavor, which helps preserve the ingredients.
Because of the strong flavor, tsukudani has been served as a side dish to accompany plain steamed rice since the Edo period (1600s–1800s). We call it gohan no okazu (ご飯のおかず), or rice side dish, as it’s eaten with steamed rice as a flavoring agent.

What is Kombu Tsukudani?
Kombu tsukudani (昆布の佃煮) is one of the most common types and it’s an excellent way to use up all your spent kombu. Other typical ingredients to make into tsukudani are seafood/fish (like baby sardines), shellfish, meat, seaweed, and vegetables.
Kombu tsukudani keeps for up to 2 weeks in the fridge, so it’s a great dish to make ahead and keep on hand. Tsukudani is always served and eaten chilled from the refrigerator and is not cooked again prior to eating.
Why You’ll Love This Recipe
- Repurpose spent kombu – Save those leftover kombu pieces in the freezer until you have time or enough kombu to make this dish.
- Great meal prep dish – It’s one of Japan’s delicious plant-based dishes that you can add to your meal prep recipe collection.
- Flavor booster for your bowl of rice or rice ball – Tsukudani adds a wonderful savory boost to your steamed rice or onigiri. For a spicy kick, try adding chopped dried red chili pepper!

Ingredients for Kombu Tsukudani
- spent kombu (kelp) – leftover from another use; I used hidaka kombu that‘s tender and easy to cook
- toasted sesame seeds
- dried red chili pepper (赤唐辛子) – If you like it spicy, you can add two pieces, but one is good for our family
- water
- mirin
- sake
- rice vinegar (unseasoned)
- soy sauce
- sugar – you can add more for a sweeter taste
- katsuobushi (dried bonito flakes) – optional; skip for vegan/vegetarian
The Best Kombu for Tsukudani
For the best texture, hidaka kombu (日高昆布) is the most suitable choice for tsukudani. It gets tender a lot faster than other types. Ma kombu and rishiri kombu are thick and hard to cook.
Do you know which type of kombu are you using? If not, check out my kombu post where I discuss the different types.
If you use different types of kombu in your cooking like I do, I recommend freezing the spent kombu separately based on variety. Then you can cook it according to kombu type for a consistent result.

How To Make Kombu Tsukudani
- Cut the kombu into thin strips.
- Cut the chili pepper into thin rounds.
- Simmer the kombu strips in a medium saucepan with the water, sake, and mirin. Then, add the rice vinegar, Japanese soy sauce, sugar, and optional katsuobushi. Add the red chili pepper.
- Bring the liquid to a boil over medium heat, then reduce the heat to low.
- Simmer until most of the liquid evaporates, about 20–25 minutes. If the kombu is still not tender, add water and continue to cook. Taste and adjust the seasoning to your liking.
- Sprinkle with sesame seeds.
You can store the leftovers in a jar or other airtight container in the fridge for up to 2 weeks. Serve it chilled.
3 Tips for Tender Kombu Tsukudani
Here are my tips for making delicious, tender kombu tsukudani:
1. Choose the right type of kombu.
If you plan to make kombu tsukudani, pick a tender variety of kombu like hidaka kombu. But sometimes you just have to use whatever kombu you have. In that case, try my next tip #2.
2. Add rice vinegar while simmering.
In Japan, kombu is often cooked with a little bit of rice vinegar, which tenderizes the kombu. Don’t add too much though. You don’t want the tsukudani to taste vinegary.
3. Refill the water and cook until tender.
If the kombu hasn’t turned tender after simmering for 20–25 minutes, add some water and continue to simmer until it gets to the right texture.

Wish to learn more about Japanese cooking? Sign up for our free newsletter to receive cooking tips & recipe updates! And stay in touch with me on Facebook, Pinterest, YouTube, and Instagram.

Kombu Tsukudani (Simmered Kombu)
Ingredients
- 2 oz used kombu (kelp) (you can use up to 4 oz (113 g); I used spent Hidaka kombu that‘s tender and easy to cook; Ma kombu and Rishiri kombu are thick and hard to cook; read about the different types of kombu)
- ½ tsp sesame seeds
For the Seasonings
- 1 dried red chili pepper
- 1 cup water
- 1 Tbsp mirin
- 1 Tbsp sake
- 1 tsp rice vinegar (unseasoned)
- 2 Tbsp soy sauce (or more, if needed)
- 2 tsp sugar (or add more for a sweeter taste)
- ½ tsp katsuobushi (dried bonito flakes) (optional; skip for vegan/vegetarian)
Instructions
- Gather all the ingredients.
- Cut 2 oz used kombu (kelp) into thin strips.
- Remove the seeds from 1 dried red chili pepper and cut it into thin rounds.
- Transfer the sliced kombu to a medium saucepan. Add 1 cup water, 1 Tbsp sake, and 1 Tbsp mirin.
- Add 1 tsp rice vinegar (unseasoned), 2 Tbsp soy sauce, 2 tsp sugar, and ½ tsp katsuobushi (dried bonito flakes).
- Add the red chili pepper. Bring the liquid to a boil over medium heat.
- Once boiling, reduce the heat to low and simmer until the liquid is almost evaporated, about 20–25 minutes. If the kombu is still not tender, add water and continue to cook. Check the taste and add more sugar and/or soy sauce, to your liking.
- Sprinkle ½ tsp sesame seeds on top. It‘s ready to serve.
To Store
- Keep the Tsukudani in the refrigerator and consume within 2 weeks.
Is there a good substitute for katsuobushi in this? I would like to make a vegetarian version.
Thank you!
Hi Leona!
You may skip the Katsuobushi or use Shiitake mushroom instead.
We hope this helps!
Thank you! How would one use shiitake mushrooms in this?
Hi Leona!
It is our pleasure!
You can thinly slice the Shiitake mushrooms and add them at Step 4.
If you are using the dried Shiitake mushrooms, let them soak in the water and make Shiitake dashi stock, then use the dashi instead of the water for this recipe. You may also add the soaked Shiitake mushrooms at Step 4 as well.
We hope this helps!🙂
I have a question about the KOMBU TSUKUDANI recipe. When you say”Add the red chili pepper and bring the mixture to a boil.” Do you mean that the kombu can boil? I thought that kombu may not boil, or is this incorrect? Thanks!
Hi Sien!
If you are making Dashi from Kombu and extracting the Umami from it, yes, you can not boil the Kombu in the water.
In this recipe, we cook with a Sauce and adding flavor to the used Kombu, so it is OK to bring the sauce to a boiling point and reduce the heat to simmer.
We hope this helps!
What non-alcoholic alternatives would you recommend for sake and mirin?
Hi Fairuz!
The non-alcohol mirin is available. As for Sake, you may replace the amount with water or broth.
You can learn more about substitutes in these posts.
https://www.justonecookbook.com/mirin/
https://www.justonecookbook.com/sake/
We hope this helps!☺️
Had a rather funny experience with this one. I cannot find katsuobushi anywhere nearby, so I was forced to attempt this recipe without any (I’d had my kombu frozen for about a month, so I needed to use it). The result was alright (although my partner disliked it), but I found myself thinking it could really use some fish. Whoops!
Ah well, hopefully by the time I’ve amassed another round of kombu I’ll have all the proper ingredients. In the meantime I’ll just have to find the right stuff to eat it with I suppose.
Hi DC,
Thank you very much for trying this recipe!
If you can’t find or use Katuobushi, we recommend substituting it with the Shiitake mushroom. It will add more flavor to this dish. We hope this helps!
Hello,
I used to get riceballs from my high school friend w/ this kombu inside and loved it! I was able to purchase it by the packets already cooked. Do you know where I can purchase it already prepared (on line maybe)?
Hi Jahnna!
You can purchase these types of kombu in refrigerated sections of Japanese/Asian grocery stores. You can also purchase Shio Kombu on Amazon (https://amzn.to/3dF4iIF).
We hope this helps!
I had no idea type of kombu I had until I checked the packaging and it is the type you recipe recommended. I had just made the spinach with kombu and I immediately tried this recipe. I am so impressed. Such flavoring with so little effort. The chili definitely gave it a strong kick. The family loves it!!
Hi Maggie! Aww I’m glad to hear that you and your family enjoyed this simple dish! Thank you for your kind feedback. xo
I feel so fortunate to have found this website, Japanese food has always been intimidating to me but your recipes and explanations of ingredients are so helpful! I just made this recipe for the first time, but didn’t have sake or bonito flakes. I tried it anyway since I had a bunch of Kombu and it was SO delicious! My family loved it, now everyone would like us to always have a container of it in the fridge for snacking. Thank you! If you ever release a cookbook I’ll be in line to get it!
Hi Nathalie! Thank you for your kind feedback. I’m so happy to hear you enjoyed this recipe and my recipes. It meant so much to me that you enjoy cooking Japanese food at home! 🙂
And thank you for your interest in my cookbook. Maybe one day… we’ll see. 🙂
Thank you so much for your beautiful recipe. I will certainly make it for my family. When you say ‘used kombu’ – do you mean if you use kombu to make soup or dashi? Kombu is boiled and then taken out? — does the nutrition of the kombu remain in the soup and still remain in the kombu pieces as well? If I want to add the goodness and ‘umami’ of kombu to cooking oil – can I just leave the kombu in the oil? – how long should I leave it for? Have you tried doing this? – would it work you think? Sorry I have so many questions. I am very interested in food and it’s health value as well.
Hi Virginia! Yes, that’s correct. The kombu that you take out from making dashi. I think the nutrition and fibers remain in the kombu, but it’s more like for enjoying the texture and not wasting the edible food. Adding to the oil… Not sure if that would work, especially with the used kombu. Not much flavor left. 🙂
Hi – I cannot figure out what type of kombu this is (and whether it would be suitable for Kombu Tsukudani): Wel-Pac Dashi Kombu Dried Seaweed. Can you please let me know?
Hi JP! This one is to make dashi (especially package said dashi kombu) and it’s a bit lower quality (especially if they don’t want to say which t type of kombu)… so it’s possible that the kombu stays too tough even after cooking for a long time. Hidaka Kombu gets tender nicely.
https://www.justonecookbook.com/kombu/
This was lovely! I always wondered if I could reuse or somehow eat kombu after making broth from it and this was the perfect sidedish. Thank you for sharing the recipe!
Hi Heeyoung! Thank you so much for trying this recipe. I’m so glad you could reuse your kombu and liked this dish. Thanks fo your kind comment! xo
Hey Nami,
I found it hard to cut the kombu in even stripes because of it’ sliminess.
And I can’t figure out which kind of kombu. It only says dashi kombu, dried kombu. I ordered from Amazon, wel-pac is the name of the company. Think i’m gonna use tip 2.
First I waa freezing it until I got time in my cooking plan. Thanks for this too.
Have a nice day when you read this
Hi Anna! Kombu has different varieties (https://www.justonecookbook.com/kombu/) and some type of kombu can remain tough even after simmering. The great kombu for simmering is Hidaka Kombu – they are tender and so easy to eat. Kombu packages/brands (such as Wel-pac) don’t show which type of kombu…and they tend to be not higher quality. When it says “Dashi Kombu”, the name is too general and it’s mostly lower grade. I get kombu that is a bit more expensive than those brands from the Japanese market here, and they are decent (but not as great as ones we can buy in Japan). So if possible, get ones that specify what type of kombu. Hope this helps!
This is a great recipe but I have a question! I tried making this with 16oz of kombu instead of 2oz since I use it very often because I love it so much… I multiplied the ingredients by 4 instead of 8 because I thought it’d be too salty (except the katsuoboshi, I left that alone)… it still came out very salty! Should I have stuck to the original measurements?
Hi Alex! It’s Tsukudani so it is supposed to be salty per se: 1) to keep the food for a longer time (preserved food) and 2) to eat small amount with steamed rice – it’s like a condiment. However, I’m not sure how salty yours was… the kombu takes a long time to get tender, so it cooks for a long time. If you feel it was too salty, reduce the amount of soy sauce. But it’s not something we eat it by itself too. 🙂
Oh! Sorry, maybe I wasn’t clear enough, my bad.
I actually am of Japanese heritage, my father is Polish-American but my mother is a mix of several European heritages and Japanese. However I did not grow up eating much Japanese food because of limited access and my mother did not know how to cook it. We did however eat a lot of short grain rice.
I started teaching myself how to cook Japanese food about 13 years ago as a late teenager. I am aware this is salty and eaten with rice. What I meant was I tried making a large batch and messed up somewhere because it was unbearably salty!
Thank you for the response, I hope you have a great day 🙂
Hi Alex! Wow, you’ve been cooking Japanese food for a long time! That’s wonderful!!! It’s possible that the liquid evaporated faster and saltier. Add water to dilute when you need to cook for a longer time will help. Also adjust soy sauce (gradually add). Since you have more kombu to cook, that might be helpful. 🙂
It has been a long time but I still consider myself a student! I continue to learn all the time. Your blog is especially great, you have so many neat and unique recipes.
Thanks for the tips!! I’ll try that next time. 🌸
Thank you so much for your kind words, Alex! Happy cooking!
Thank you for sharing. This is easy and delicious. I’ve learned so much from your recipes. 🙏
Hi Ursula! Thank you so much! I’m glad you enjoy my recipes. 🙂
awesome. i recognize this as one of the things i had but did not know what it was in japan! thank you again. i am learning and loving your site so much!
Aww thank you so much Grace! Hope you enjoy making all the Japanese dishes back home that you enjoyed in Japan!
I would love to see you publish a hard cover cook book. Problem with kindle is you have to print out the recipe if you don’t have a tablet. If I am camping off grid and want to cook something without WIFI I can’t see the book.
I do enjoy your recipes and am learning the terminology, because your posts are thorough and easy to follow.
Hi Mary! Thank you so much for your interest in my hardcover cookbook. 🙂 Maybe one day with the right publisher and timing, I’ll be able to write a cookbook. Right now, my time is dedicated to sharing free recipes on my website and YouTube channel so people in the world will get to cook Japanese food at home. This takes up so much of my time (besides raising 2 kids). If you enjoy my recipe, please use a print out button in the recipe card to collect in your binder. Hopefully, I can write a book after my kids go off to college!