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Home » Recipes » Dashi

Two Ways to Make Kombu Dashi (Kelp Broth)

Published: Oct 20, 2022 | Modified: May 3, 2025 By Ryo Hikita | Leave a Comment

Kombu Dashi is one of the most essential broths in Japanese cuisine. Kombu is rich in umami components that enhance the flavor of soups and simmered dishes. It is very easy to make with just kombu and water.

↓ Step-by-Step Recipe  

kombu dashi
Jump to:
  • What is Kombu Dashi?
  • The source of umami
  • Extraction methods
  • Optional preparation
  • 📋Step-by-step recipe
  • Tips on how to make
  • Next Step
  • Recipe card

What is Kombu Dashi?

Kombu Dashi is a type of dashi broth made from dried kombu (kelp). Kombu contains a large amount of amino acids that humans perceive as umami, enhancing the flavor of dishes. It has been widely used in Japanese cuisine since ancient times and continues to be one of the most popular types of dashi today.

The source of umami

The true essence of umami in kombu dashi lies in its glutamic acid and aspartic acid. In particular, glutamic acid was the first umami component in the world to be discovered from kombu, which also led to the creation of the term 'umami.'

While you might fully appreciate the deliciousness of these amino acids when drinking kombu dashi on its own, you will find that they enhance the flavor of dishes when used in cooking, making them even more flavorful.

kombu

Extraction methods

There are two methods for making kombu dashi: cold brewing and simmering.

• Cold brewing

Simply soak the kombu in a bowl or bottle of water to extract its flavor. Since there is no need to heat the kombu, you can easily make kombu dashi.

It has a delicate flavor, making it suitable for dishes like suimono and sumashijiru (both are traditional Japanese soups with dashi as the main component), as well as dishes where you want to highlight the natural flavors of the ingredients.

• Simmering

Rehydrate the kombu in water until it softens, then simmer it in the same water. This method is quicker than cold brewing and results in a stronger flavor with a richer umami taste.

It pairs well with various Japanese dishes and is the most common method for making kombu dashi.

You can use either method to make kombu dashi, so feel free to choose the one you prefer. Personally, I always use the simmering method.

Optional preparation

The preparation before making kombu dashi is not necessary, and I don’t do it, but if you are concerned about any dust on the surface of the kombu, you can quickly wipe it off with a well-wrung damp cloth.

At this point, avoid rinsing it with water, as this will wash away the umami components of the kombu. The white powdery substance on the surface of the kombu is a natural flavor enhancer, so it is best to leave it on.

kombu dashi

📋Step-by-step recipe

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Ingredients

Servings: 2

US Customary - Metric
  • 0.17 oz kombu (dried kelp) (The amount of kombu should be approximately 1% of the water volume.)
  • 2 cups water
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Instructions

🕒 Total 3 hrs or 40 mins

Cold brewing method:

kombu dashi instruction_1-1

Step 1
Put water and kombu in a pot or bowl, and let it soak for 3 to 9 hours. After soaking, remove the kombu.


Simmering method:

kombu dashi instruction_2-1

Step 1
Put water and kombu in a pot and let it sit for at least 30 minutes until the kombu softens.


kombu dashi instruction_2-2

Step 2
Heat the pot over very low heat for about 10 minutes (for 2 servings). When small bubbles appear on the surface of the liquid, turn off the heat and remove the kombu.


To store

You can store it in the refrigerator for up to 3 days or in the freezer for up to a month.

Tips on how to make

  • Use as large a piece of kombu as possible. Since kombu releases its slimy components from the cut surfaces, the fewer the cuts, the clearer the flavor will be.
  • Be careful not to soak the kombu in water for too long. If you soak the kombu for more than 10 hours, the water (kombu dashi) may become cloudy and develop a strong kombu odor.
  • Even when simmering, soak the kombu in water for at least 30 minutes. Kombu that hasn't been soaked will not yield as much dashi.
  • When simmering, cook slowly over very low heat. High heat will not bring out the full flavor of kombu. Additionally, remove the kombu before the liquid starts to boil. Once small bubbles appear on the surface of the liquid, it is a sign to take it out. As the water comes to a boil, the distinct odor of kombu will become stronger, and the kombu will release its slimy components.

If you try this recipe, I’d love to hear what you think. Please consider leaving a review and star rating in the comments below. If you enjoyed it, I’d really appreciate it if you shared it with your friends.

Next Step

By using kombu dashi, you can make awase dashi by combining it with other types of dashi, such as bonito dashi or shiitake dashi.

In addition, the kombu that has been used to prepare dashi can be reused for other Japanese dishes. Be sure to try recipes for "Kombu Chips" and "Shio Kombu" (salted kelp) as well.

Recipe card

kombu dashi

Two Ways to Make Kombu Dashi (Kelp Broth)

Kombu Dashi is one of the most essential broths in Japanese cuisine. Kombu is rich in umami components that enhance the flavor of soups and simmered dishes. It is very easy to make with just kombu and water.
No ratings yet
Print Recipe Pin Recipe
Cook Time: 10 minutes mins
Soaking Time: 30 minutes mins
Total Time: 40 minutes mins
Servings: 2

Ingredients
 
 

  • 0.17 oz kombu (dried kelp) (The amount of kombu should be approximately 1% of the water volume.)
  • 2 cups water
Prevent your screen from going dark

Instructions
 

Cold brewing method:

  • Put water and kombu in a pot or bowl, and let it soak for 3 to 9 hours. After soaking, remove the kombu.

Simmering method:

  • Put water and kombu in a pot and let it sit for at least 30 minutes until the kombu softens.
  • Heat the pot over very low heat for about 10 minutes (for 2 servings). When small bubbles appear on the surface of the liquid, turn off the heat and remove the kombu.

Notes

  • When cold brewing, the total time is 3 to 9 hours.
  • You can store it in the refrigerator for up to 3 days or in the freezer for up to a month.

Nutrition

Calories: 5kcal
Author: Ryo Hikita (Umami Pot)
Cuisine: Japanese
Category: Dashi, Plant-Based, Traditional
Keyword: dashi, kombu
Enjoyed this recipe?I’d really appreciate it if you shared it with your friends.

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Welcome to Umami Pot!

I'm Ryo, a Japanese culinary expert living in Osaka, Japan. Here, I would like to share with you how to make Japanese dishes actually enjoyed in Japan, from traditional to modern, as clearly, concisely, and deliciously as possible.

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