What Is Kombu Kelp? ーHow to Use, Make Broth, and Where to Buy It

When people hear the word "kombu," some may picture health foods or superfoods. Others might confuse it with the fermented tea known as “kombucha”. However, in Japan, most people naturally think of kombu kelp, a large sea vegetable that grows in the ocean. This is because kombu is such a familiar ingredient, commonly used as a base in home cooking and found in nearly every household pantry.

This article introduces you to what kombu kelp really is, how it’s used in cooking, the nutrients it contains, how to make kombu dashi broth, and where to buy it.

What Is Kombu Kelp?

Kombu is a thick, ribbon-shaped seaweed that appears dark green to black. It has been used for centuries in Japanese cuisine and is considered one of the most important ingredients in creating deep, savory flavor. After being harvested from the sea, kombu is dried under the sun to preserve its umami-rich properties, then packaged, and shipped globally. It is typically rehydrated in water before being used in cooking.

Kombu plays a key role in making dashi, the foundational broth in Japanese cuisine. Dashi brings out umami—the fifth taste that stands alongside sweetness, sourness, saltiness, and bitterness. This depth of flavor has made kombu a popular ingredient among chefs and home cooks worldwide.

Health Benefits of Kombu Seaweed

Kombu is packed with nutrients. It contains high levels of magnesium, calcium, and iron—far more than dairy products like milk. A specific variety of kombu known as “Ma-kombu,” harvested in southern Hokkaido, is especially rich in iodine, a mineral essential for thyroid health. It is also high in dietary fiber, low in calories, and supports digestion, and blood sugar balance, making it an excellent addition to a healthy lifestyle.

What’s the Difference Between Kombu and Other Seaweeds?

In Japanese households, a variety of seaweeds are commonly enjoyed—not just kombu. For example, nori and wakame are both staples in everyday meals. Nori is made by washing, chopping, drying, and roasting edible seaweed such as Susabi nori or Asakusa nori. Its fragrant, crisp sheets are used to wrap rice in dishes like sushi rolls. Wakame, on the other hand, is often found in miso soup and salads. If you’ve had a "seaweed salad" at a Japanese restaurant, chances are it was made with wakame.

Another use is “maze wakame” which can be mixed into freshly cooked rice for a tasty seaweed flavored rice or even shaped into rice balls. So, how is kombu used differently? Compared to other seaweeds, kombu is thicker, has a deeper flavor, and is especially rich in minerals. These qualities make it an essential ingredient in Japanese cooking, particularly for making dashi—a soup stock that concentrates the savory essence known as umami.

How to Use Kombu in Japanese Cooking

Making Kombu Dashi

Kombu dashi is a plant-based stock commonly used in both home kitchens and restaurants. The process is simple: soak dried kombu in water for at least an hour. Then heat it gently without boiling. Just before the water reaches a boil, remove the kombu to avoid any bitterness or sliminess that can come from overcooking.

This kombu broth can be used on its own or combined with bonito flakes or dried sardines to make a stronger blend called “Awase-dashi”. These Dashi are used in dishes like miso soup, simmered vegetables, Japanese-style omelets, and ramen. Dashi made from 100% natural ingredients without fish products areis gaining attention among vegans and health-conscious people around the world for its rich, umami flavor

Cooking with Kombu Dashi

Using kombu dashi can elevate simple ingredients like vegetables, chicken, or tofu. It enhances their natural flavors and provides a nourishing depth that’s hard to achieve with regular broths. 

See the recipe for Chicken Wings with Salt Koji Hot Pot

What’s Kombu Used For?

In Japanese cuisine, kombu is used in many traditional dishes beyond dashi.

Oden

Oden is a classic Japanese hot pot dish typically enjoyed in colder seasons. It features simmered ingredients like boiled eggs, daikon radish, fish cakes, beef tendon, and tied kombu strips. The kombu contributes both as a flavoring agent and as an edible component.

Kombu Onigiri

Used kombu from making dashi can be repurposed. By simmering it with soy sauce and mirin, you can make tsukudani—a savory kombu preserve that pairs well with rice. It’s often used in rice balls (onigiri), making them a favorite snack for people of all ages in Japan.

Kombu-maki

Kombu also holds cultural significance. Its name sounds like “yorokobu,” which means “to rejoice,” making it a lucky ingredient in celebratory meals. A dish called kombu-maki, where fish like salmon or herring is wrapped in kombu, is a traditional offering in osechi, Japan’s New Year meal set.

Yudofu

For a simple and pure kombu experience, try yudofu—tofu gently warmed in kombu dashi. It allows you to taste the true essence of the kelp, especially when made with premium varieties like Rishiri kombu, known for its delicate aroma and clarity of flavor.

Kombu adds a deep marine richness to every dish it touches. From everyday meals to seasonal celebrations, kombu brings quiet but essential flavor to Japanese cooking. You may find your own favorite way to enjoy it, whether in soup, with rice, or simply as a natural broth.

Where to Buy Kombu Kelp

You can find kombu online or in Asian grocery stores, especially those that specialize in Japanese products. When choosing kombu, consider its origin. Ma-kombu (from Hakodate in southern Hokkaido) is regarded as one of the highest quality varieties. Rishiri kombu (from Rishiri Island in northern Hokkaido) and Rausu kombu from the Shiretoko Peninsula are especially popular for making dashi. Rausu kombu produces a rich and deep broth that stands well on its own. Hidaka kombu (from Hidaka region in south-central Hokkaido) is another versatile option, used both for making stock and as an edible ingredient.

For rice dishes or snacks, look for pre-cut or shredded kombu that’s ready to use. Whether you’re using it for cooking or eating, there’s a wide variety to explore depending on your dish.

📍Save These Delicious Kombu Ideas on Pinterest!

Recommended Products:

Premium variety pack　Enjoy top-quality kombu in a range of flavors and cuts.

Seaweed salt　A rich blend of seawater and seaweed umami—perfect for finishing dishes.

Maze wakame　Just mix with rice for an easy umami-packed meal.