Kombu is edible dried kelp used in Japanese cooking and the umami backbone of many Japanese dishes. It is used to make dashi and is also used as an ingredient in tsukudani and simmered dishes. Making kombu dashi is very simple, but a few tips make a huge difference. Once you know how to make kombu dashi, you can make a lot of umami-rich Japanese dishes at home.
Kombu is one of the items I keep in my pantry all the time to make daily meals, from miso soup and hot pot to traditional celebratory dishes like Datemaki for New Year Osechi Ryori.
Use kombu dashi to make miso soup to serve in a teishoku-style meal with Karaage and Sunomono. After making dashi, save the softened kombu to make kombu no tsukudani and kombu onigiri.
Jump to:
What Is Kombu?
Kombu (昆布) is edible kelp commonly used in Japanese cooking. It's usually sold in dried form, dark green or brown in color, and has a stiff texture. When rehydrated, it becomes smooth, flexible, and almost leather-like in texture.
In Japanese cooking, kombu is often used for making umami-rich dashi broth called kombu dashi (昆布出汁). Making kombu dashi is easy, and it adds satisfying savory umami to miso soups, simmered dishes, hot pot, and dashimaki tamago.
Knowing the kombu basics is so useful for both when you're cooking from scratch or with kombu products!
Kombu in Japanese Cooking
Kombu is a key pantry ingredient in the Japanese kitchen. It is rarely the star of the dish, but it creates an umami foundation of many Japanese dishes, especially when combined with bonito flakes in dashi. Kombu creates subtle yet complex, umami-rich dashi.
Even if you're not using dried kombu directly, it's used in many Japanese products, from dashi packets and premade dashi to ponzu, snacks, and some potato chips.
You can also use kombu as an ingredient to make traditional Japanese dishes like kombu no tsukudani, kobumaki, and simmered kombu and beans.
If you're living in Japan, kombu is your closest neighbor without realizing it. It's in a lot of soup bases, dishes, and snacks as a flavor base.
What Does Kombu Taste Like?
When kombu is cooked until tender, it tastes savory, ocean-like, and subtly umami. And don't worry, it's not too fishy at all!
Dried kombu has a rich, savory aroma that is so satisfying. Dried kombu is edible, but I don't recommend eating it because it's really sharp and hard. It's much more enjoyable when it's softly cooked.
Kombu Products
Dried kombu is a basic pantry item for making dashi. There are kombu products that make kombu easily enjoyable!
- Shio kombu (塩昆布): thinly sliced kombu strips are cooked and seasoned with soy sauce or salt-based seasoning, then dried and coated in salty seasoning. You can mix it in rice to make onigiri, massage it with veggies to make asazuke quick pickle, or add it to ochazuke.
- Tororo kombu (とろろ昆布): dried kombu is soaked in vinegar to tenderize, and kombu sheets are pressed together to form a block. Then the side of kombu is thinly shaved by machine to create fluffy strands. It has a melt-in-your-mouth texture that is great for adding to soups.
- Oboro kombu (おぼろ昆布): Similar to tororo kombu, dried kombu is tenderized in vinegar and shaved thinly. But unlike tororo kombu, the surface of the kombu is thinly shaved by hand into sheets. It creates a delicate texture perfect for wrapping onigiri.
Along with dried kombu, I like keeping shio kombu and tororo kombu on hand to make simple onigiri and quick pickles. Oboro kombu is often pricier than tororo kombu because it is usually made with premium kombu and involves more manual labor. But its delicate texture is so special.
Types of Kombu: Which One Should Beginners Buy?
For your first kombu, buy regular dried dashi kombu from a Japanese or Asian grocery store. It's great for making everyday dashi.
Dashi kombu products often do not specify which type of kombu is used, but are precut in easy-to-use sizes and affordable. You can simply steep it in water or gently cook it to make dashi.
If you want to make osuimono, Japanese clear soup, or other umami-centric dishes where you want kombu dashi to shine, try using higher-quality kombu varieties. I recommend ma kombu or rishiri kombu for a clear, elegant taste, and rausus kombu for a bold, full-bodied taste.
Common Kombu Varieties You May See
There are many types of kombu used in Japan. Most of the Japanese kombu is harvested in Hokkaido, the northern part of Japan. Depending on the environment of the sea it grows in, texture and taste change, and each type has its own name.
- Ma kombu (真昆布): kombu from the Hakodate coastline area. It is thick and creates clear, sophisticated dashi with a hint of sweetness. This premium-grade kombu is often used in ryotei (high-end traditional Japanese restaurants).
- Rishiri kombu (利尻昆布): kombu from Rishiri Island, Rebun Island, and the Wakkanai coastline area. It has a rich aroma and creates a clean, sophisticated taste of dashi with a gentle natural saltiness. It's also often used in ryotei.
- Rausu kombu (羅臼昆布): kombu from the Rausu coastline area. It's a wide brown kombu that creates dashi with a bold, rich taste and yellowish color.
- Hidaka kombu (日高昆布): kombu from the Hidaka coastline area. It softens more easily, so it is good for both making broth and eating in simmered dishes. It has a mild, ocean-like flavor, great for everyday cooking.
When I was teaching plant-based cooking in Japan, taste-testing dashi made from all the different kombu was one of the students' favorite activities in the class. While they're all kelp, they all taste slightly different from each other, and everyone has their own favorite. It's truly magical what nature creates!
My favorite is Rishiri kombu, but I find it difficult to find it in the US. So if you get a chance to get your hands on it, give it a try and taste the difference!
Where to Buy Kombu
I usually get kombu at a local Asian grocery store and also find it in the Asian food aisle at regular grocery stores. You can also find it at Japanese grocery stores and online. Look for dried kombu that's sold as a pantry item.
For beginners, look for packages saying kombu, konbu, dashi kombu, or dried kelp. The selection in the US supermarket might be small, but that's ok! You don't need premium kombu to make everyday miso soup, so grab what you can find. If your goal is to make dashi, choose dried dashi kombu instead of seasoned kombu products like shio kombu or tororo kombu.
Some kombu products are sold as large sheets, while others are already cut into smaller pieces. Precut dashi kombu is convenient for everyday cooking because you can just add a piece directly to water, rice, soup, or hot pot, and it usually cooks faster.
What Is the White Powder on Kombu?
White powder on the kombu may look scary at first, but don't worry! Chances are, it's natural flavor compounds that crystallized on the surface of dried kombu. It is part of what gives kombu its umami and subtle sweetness, so it's something you want to keep in your dish!
So, do not wash off the white coating on the kombu or rinse the kombu under running water before use. If you see any dust or grit on the surface, gently wipe it off with a lightly damp cloth.
It is also important to know that white mold can grow if kombu is not stored properly. In that case, mold usually looks fuzzy instead of powdery. If it smells musty, feels damp, or looks moldy, discard it and use a fresh package.
How to Use Kombu
The most common way to use kombu is making dashi, but kombu is way more than that! If you love Japanese food, you will find kombu in many dishes. It creates a subtle yet powerful umami foundation in many dishes.
Kombu Dashi
Making kombu dashi is the most classic way to use kombu. Kombu dashi is a simple Japanese broth made with dried kombu and water. Kombu dashi has a clean, subtle umami flavor and works beautifully as a base for miso soup, noodle soup, simmered vegetables, hot pot, and agedashi tofu.
Kombu is often combined with other umami sources like katsuobushi and shiitake mushrooms to boost umami in dashi. We'll cover more about this in the Umami Synergy section.
Cooking Rice with Kombu
This is a simple trick to elevate your everyday rice! Kombu adds subtle umami and brings out the natural sweetness of the rice.
You can just add a 4-5" piece of kombu into a pot of rice before cooking, or use kombu dashi to cook the rice.
Tsukudani and Furikake
When I was working at a plant-based cooking studio, one of the most common questions was "what to do with kombu after making dashi?" So, making tsukudani and furikake is a great way to use it.
Tsukudani is a savory simmered side dish. I call it Japanese savory jam, but instead of bread, you'll enjoy it over steamed rice. Furikake is similar to tsukudani, but with a dry to semi-dry texture, and sprinkle it over rice to enjoy.
After making dashi, cut the kombu thinly and freeze it. Once you have saved enough kombu, cook it with soy sauce, mirin, and other seasonings to make tsukudani or furikake.
Hot Pot and Yudofu
Kombu is used in many soup bases. Yudofu is a simple hot pot made by gently simmering silken tofu in kombu dashi. Enjoy the tofu with ponzu and aromatics like grated daikon and grated ginger.
Asazuke Quick Pickles
Asazuke is a simple Japanese quick pickle made by tossing vegetables like napa cabbage and cucumber with salt. Salt extracts excess moisture from the vegetables, which results in a crunchy texture and condensed natural flavor, making them simple yet so satisfying. Asazuke made with kombu is even more delicious, with a boost of umami.
If you want to recreate it at home, toss sliced cucumber with salt and a few small pieces of kombu. Use salt that weighs about 2% of the cucumber's total weight. Add weight on top and refrigerate for a few hours. You'll get crunchy asazuke ready to serve in a Japanese breakfast with grilled salmon, miso soup, and rice.
Anko and Azuki Beans
My personal favorite way to use kombu. Kombu helps tenderize beans and makes them digest easier.
When I make anko, sweet red bean paste, from scratch, I always add a piece of kombu to add subtle umami and a hint of saltiness.
When I was learning macrobiotic cooking, I learned that azuki beans and kombu are considered a balanced combination. I really love this flavor combination with kabocha and make azuki kabocha every winter. All you need is a pinch of salt and a gentle simmer to bring out their natural sweetness.
How to Make Kombu Dashi
Ingredients
All you need is two ingredients: kombu and water.
The basic ratio is kombu that weighs about 1% of the water weight. For example, with 2 cups (480ml) of water, you'll need about 5g of kombu.
You don't need to be too strict, but this ratio is a good starting point for clean, subtle kombu dashi. If you want a stronger flavor, you can use a little more kombu or let it steep longer. You can also make a few cuts in kombu to help release more flavor.
One time I added too much kombu to make cold brew dashi, and it ended up very slimy. So my rule of thumb is to use kombu that weighs about 1% of the water weight, or up to 2% if you want a stronger dashi.
Also, the hardness of the water can affect how kombu steeps. In Japan, water is usually soft water, which extracts umami well. On the contrary, very hard water can make dashi taste less clean or less balanced. This may be one reason your kombu dashi tastes weaker or less clean than the dashi you remember from Japan.
Some professional chefs outside Japan select their cooking water carefully. For home cooks, you can use bottled soft water ot filtered water. You can also combine it with bonito flakes to make a stronger dashi.
Simple Kombu Dashi Method
There are two ways to make kombu dashi: stovetop and cold-brew methods. So choose the method that fits your lifestyle and the taste you're looking for.
- Stovetop method: gently simmering kombu in water to create rich, bold dashi.
- Cold-brew method: soaking kombu in water for longer hours to create clear, sophisticated dashi.
Even if you use the same type of kombu and water, the taste of the dashi changes depending on your cooking method.
Stovetop method
- If you see any dust or grit on the surface, gently wipe it off with a lightly damp cloth. Do not wash off the white coating on the kombu or rinse the kombu under running water before use.
- In a pot, combine the kombu and water. Let it soak for 30 minutes.
- Cook the kombu and water over low heat and let it simmer until just before boiling. Remove the kombu and use the dashi in your favorite recipes. Do not let it boil. Boiling can make the dashi less clean or slimy.
- Discard kombu or use it in tsukudani or other recipes.
Cold-brew method
- If you see any dust or grit on the surface, gently wipe it off with a lightly damp cloth. Do not wash off the white coating on the kombu or rinse the kombu under running water before use.
- In a jar or bottle, combine water and kombu. Secure the lid and refrigerate for at least 3 hours, preferably overnight.
- Remove the kombu and use the dashi in your favorite recipes. Discard the kombu or use it in tsukudani or other recipes.
Umami Synergy
True magic happens when different types of umami sources are mixed together. It is known that umami can be multiplied when different types of umami compounds meet, creating richer, deeper, more complex flavor. This is called umami synergy.
Kombu is rich in glutamate, one of the compounds responsible for umami. When kombu is combined with ingredients rich in nucleotide-based umami compounds, like katsuobushi or dried shiitake mushrooms, the savory taste becomes more intense than using just one ingredient alone.
That is why classic Japanese dashi is often made with kombu and katsuobushi. Kombu creates a clean, gentle umami backbone, while katsuobushi adds rich, savory depth. For a plant-based dashi, use kombu and dried shiitake mushrooms.
You don't need to understand the science, but you'll taste the difference! Here are some examples of glutamate and nucleotide food combinations, and I'm sure you've seen these combos before.
- Kelp and bonito flakes
- Kombu and dried shiitake mushrooms
- Tomato and beef
- Onion or leek and chicken
That's why kombu creates a great base for many dishes, enhancing the natural flavor of the ingredients it's combined with.
Kombu vs Wakame
Many kinds of seaweeds are used in Japanese cooking, so it's nice to know which to use when. Kombu and wakame are both Japanese seaweeds, but they serve very different purposes.
Kombu is thick, stiff kelp that is usually sold in dried form. It's a common ingredient to make Japanese dashi. After making dashi, use softened kombu to make side dishes like tsukudani.
Wakame is thinner and more delicate. It is usually rehydrated and eaten in dishes like miso soup, seaweed salad, sunomono, and other side dishes. Once soaked, wakame becomes silky, tender, and easy to eat.
What to Do With Kombu After Making Dashi
Don't throw away the kombu after making dashi! The great part of kombu is that you can reuse it for making other recipes.
One way to do so is to slice the used kombu thinly and save it for kombu tsukudani, a sweet and savory simmered side dish. Tsukudani is usually seasoned with ingredients like soy sauce, mirin, sake, and sugar, and it is delicious with steamed rice, onigiri, ochazuke, or a simple Japanese breakfast.
If you don't have enough used kombu yet, cut it thinly and freeze it. Once you have saved enough kombu, cook it with soy sauce, mirin, and other seasonings to make tsukudani or furikake.
You can also cut it into bite-size pieces and bake or microwave it to make kombu chips. When simmered with soybeans and seasonings, it can be a traditional simmered side dish.
I love the no-waste part of Japanese cooking because one piece of kombu can first make dashi, then become another rice-friendly side dish.
How to Store Kombu
Store dried kombu in a cool, dry place away from direct sunlight, heat, and moisture. Once opened, keep it tightly sealed in the original package, a zip-top bag, or an airtight container.
Kombu absorbs moisture and smells easily, so avoid storing it near strongly scented ingredients. If your kitchen is humid, sealing it well is especially important.
Dried kombu can last a long time when stored properly, but the flavor and aroma are best when it is fresh. If the kombu smells musty, feels damp, or shows signs of mold, it is better not to use it.
The white powder on kombu is usually natural and flavorful, but fuzzy mold, strange smells, or damp spots are different. When in doubt, trust your senses and use a fresh package.
More Japanese Basics
- What is Matcha?
- What is Koji? Japanese Fermentation Culture
- What is Shiratama Dango?
- What is Wakame?
- How to Make Shio Koji
- How to Eat Natto
Kombu Dashi
Ingredients
- 5 g kombu 1% of the water weight
- 2 cups water (480ml)
Instructions
Prepare the Kombu
- If you see any dust or grit on the surface, gently wipe it off with a lightly damp cloth. Do not wash off the white coating before use, as it contains natural flavor compounds that contribute to kombu's savory taste and subtle sweetness.
Stovetop Method
- In a pot, combine the kombu and water. Let it soak for 30 minutes.
- Cook the kombu and water over low heat and let it simmer until just before boiling. Remove the kombu and use the dashi in your favorite recipes. Do not let it boil. Boiling can make the dashi less clean or slimy.
- Discard the kombu or use it in tsukudani or other recipes.
Cold-Brew Method
- In a jar or bottle, combine water and kombu. Secure the lid and refrigerate for at least 3 hours, preferably overnight.
- Remove the kombu and use the dashi in your favorite recipes. Discard the kombu or use it in tsukudani or other recipes.
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