Seriously Asian: A Guide to Dashi

"A recipe for dashi can be as simple as water and kelp, but adding bonito makes the dashi more complex and complete."

Kelp in a pot. [Photographs: Chichi Wang]

In Japanese cuisine, all roads lead back to dashi, the base stock made from dried kelp (seaweed) and dried fish. Even in a sushi class with Morimoto I took recently, he demoed the proper preparation of dashi well before he broached the topic of fish. Perusing through a Japanese cookbook, you reach the same conclusion: without dashi, most of the recipes could not be executed.

Despite the importance of dashi, many cooks still aren't sure how to make and use the stock. Cooks with traditional French training will wonder where the mirepoix and piles of bones come into play, or how it's even possible to make a stock in under a half-an-hour. The simplicity of dashi is indeed one of its most amazing features. It really can be made in thirty minutes from start to finish and requires just two ingredients: kelp (kombu) and dried bonito (a relative of the tuna).

That being said, it takes a bit of practice to know when to remove the kombu and bonito in order to extract the right amount of flavor. Plus, there's straining involved. Any recipe that calls for a strainer can't be entirely effortless. Thomas Keller mentions in one of his cookbooks that "if in doubt, strain." Each day I spend in the kitchen reaffirms the truth of this pithy claim. I often find myself relying on the strainer to smooth out a puree or, in the case of dashi, strain the excess from the stock.

1 + 1 = 100



"What exactly is kelp?" asked someone in the Morimoto class.

In the package, kombu resembles layers of thick, black parchment. Recognizable by its brown leafy fronds, the type of kelp (kombu) we eat is a species of large, floppy seaweed that grows in shallow ocean waters. At some point in the early 1900s, Japanese scholars discovered that the active ingredient in kombu is actually a naturally occurring form of MSG called glutamic acid. Professor Ikeda, the researcher behind the work on kombu, named the taste of glutamic acid in its free form umami, the Japanese word that roughly translates to "deliciousness."

A recipe for dashi can be as simple as water and kelp, but adding bonito makes the dashi more complex and complete.. As one of the Japanese chefs in Morimoto's class said to me, "One plus one equals two. Kombu plus bonito is like one plus one, except that here, one plus one equals one hundred, not two."

What a clever way, I thought, for a non-English speaker to communicate the idea that the sum is much greater than its parts. Older generations of cooks would take the time to shave the bonito flakes from a block of the dried fish, whereas now, only bonito flakes can be found in Japanese markets. While it's less fresh in pre-packaged, flake form, you can preserve the integrity of the flakes by storing them in the fridge.

How to Make Dashi


Bonito flakes

To make dashi, place the kelp into a pot of cold water. Once the water is quivering, within seconds of boiling, remove the kelp and bring the stock to a full boil. Shower the stock with bonito flakes, covering the liquid's surface. Quickly, the flakes will absorb the liquid and sink like tissue paper to the bottom of the pot.

After straining the bonito flakes, the liquid becomes first dashi. First dashi is the more refined extraction, having a delicate taste and a lighter, less yellowish color. A second cooking of the kelp and bonito flakes produces the extraction called second dashi. Since second dashi is cloudier and tastes stronger than first dashi, second dashi is used in everyday miso soups and simmered dishes.

What Makes Dashi So Special?

Unlike a meat stock, dashi is light in body and adds a subtle, distinctively oceanic flavor to any dish. Freshly-made dashi is integral to miso soup, while vegetables and meats are simmered in the stock to add depth. With soy sauce and sugar, dashi forms the base for udon broth and soba sauce. Tempura sauce, so uncommonly good and suited for every vegetable, is made mostly with dashi.

Whenever I make a pot of dashi for a Japanese meal, the following days are filled with Japanese food too. Miso soup becomes breakfast, and rainy nights call for piping-hot udon noodle soup. Chawan mushi, a delicate custard made with dashi and eggs, is steamed until the surface is trembling and barely set.

The dashi possibilities are endless. Generally, I like to use the first dashi right away and freeze the second extraction for later use. While most cookbook authors and chefs will have you discard the kombu after it's used in second dashi, I like to eat the kombu. Thinly sliced and dressed in sesame oil, sesame seeds, and salt, the kombu slivers are a welcome addition to my bento box.

To begin your dashi education, start with a simple miso soup. The difference between freshly-made dashi for miso soup and the sodium-laden version found at mediocre restaurants is almost enough to make you weep with umami joy.



First Dashi

Adapted from The Japanese Kitchen by Hiroko Shimbo


Seriously Asian: A Guide to Dashi

About This Recipe


  • 2 quarts water
  • Five 6-inch squares of dried kombu
  • 1 cup tightly packed bonito flakes
  • 2 quarts water
  • The reserved kombu and bonito flakes from First Dashi


  1. 1

    To prepare the kombu: Gently wipe the kombu with a damp cloth or paper towel. The aim here is to get rid of some of the powdery excess but not all of it, since some of the umami components reside on the surface of the seaweed.

  2. 2

    Place the squares of kombu in a pot, along with the two quarts of water. Over medium heat, bring the pot of water to a near-boiling point. Take care that the water does not actually begin to bubble furiously. This process of bring the water to boil should occur slowly, over the span of 10 minutes.

  3. 3

    Immediately before the water reaches a boil, remove the kombu from the pot and set it aside for second dashi. Do not turn off the stove.

  4. 4

    After the kelp has been removed, add all the bonito flakes to the pot. Wait for a few seconds while the liquid comes to a full boil. Then turn off the heat and let the mixture stand for 2 minutes. During this time, the bonito flakes will slowly sink down into the kombu-water.

  5. 5

    Strain the stock through a fine strainer or sieve. Reserve the bonito flakes for use in second dashi. First dashi may be refrigerated, tightly covered, for up to four days or frozen in cubes in an ice tray.

  6. 6

    Second Dashi

  7. 7

    Adapted from The Japanese Kitchen by Hiroko Shimbo

  8. 8

    In a medium pot, combine the water, kombu, and bonito flakes. Cook the mixture over low heat, with the water barely simmering, for 10 minutes. Do not let the water boil, or else too much of the fishiness from the ingredients will be extracted.

  9. 9

    Strain the stock through a strainer or sieve. Discard the bonito. Discard the kombu, or reserve as an ingredient in soups or stews.

  10. 10

    Second dashi may be refrigerated, tightly covered, for up to four days or frozen in cubes in an ice tray.


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