LOX, STOCK, AND BARREL: Dashi

Dashi (wikipedia definition) is a type of soup stock; one of the most well known uses of dashi is as the base that you add miso paste to make miso soup. Dashi is also used in many other applications in Japanese cooking, similar to how French cooking uses meat stock. Dashi is actually extremely easy and quick to make. All you need to do is measure out ingredients, boil water, and strain.

The giant kelp (konbu / kombu) contributes glutamic acid to the stock, which is responsible for umami (wikipedia).

Below are two recipes for dashi; the techniques are similar, but they different in the amount of ingredients. Hiroko Shimbo's recipe uses approximately 1/2 half the quantities of konbu and katsuobushi than Shizuo Tsuji's recipe, since 1 oz = 30 grams.

Once you have dashi, you can easily make miso soup.

Paraphrased from "Fish Stock Preparation (Dashi)" from "The Sushi Experience" by Hiroko Shimbo.
Ingredients (makes 1 quart):
1 quart (4 cups) cold water
1/2 oz konbu (kelp)
2/3 oz katsuobushi (dried bonito flakes), about 3/4 cup packed or 19 grams

Soak the kelp in 1 quart of cold water overnight (about 10 hours). Alternatively, you can bring it slowly to a boil, uncovered, so that it reaches the boiling point in about 10 minutes. Remove the kelp just before the water boils because kelp emits a strong odor if boiled, and reserve it for making secondary dashi. This stock is what is called konbu dashi (kelp stock).

To make the konbu dashi into dashi, bring the stock just barely to a boil. When it comes to a boil, add the fish flakes. Count 10 seconds, and then turn off the heat. Let the stock rest with the fish flakes for 2 minutes; during this time remove any foam that rises. After the two minutes, immediately pour through a strainer lined with a wet paper towel. The bonito flakes can be reserved for making secondary dashi.

Paraphrased from "Primary Dashi" from "Japanese Cooking: A Simple Art" by Shizuo Tsuji
Ingredients (makes 1 quart):
1 quart (4 cups) cold water
30 g giant kelp (konbu / kombu)
30 g dried bonito flakes (hana-katsuo)

Add the cold water and the kelp to a soup pot. Slowly bring to a boil, uncovered, so that it will reach the boiling point in about 10 minutes. Kelp emits a strong odor if it is boiled, so it is very important to remove the kelp just before the water boils. When the water is almost about to boil, test the kelp by removing a piece and inserting a fingernail into the fleshiest part of the kelp. If it is soft, then sufficient flavor has been extracted, and you should remove all of the kelp from the stock. If it is tough, then return the kelp to the pot--keep the pot from boiling by adding 1/4 cup cold water; the kelp should be soft in about 1 to 2 additional minutes.

Arrange a fine meshed strainer (chinoise) or cheesecloth-lined sieve in a bowl that is large enough to hold the stock. Bring the stock to a full boil (the kelp should already have been removed at this point). Turn off the burner. Add 1/4 cup cold water to bring the temperature down quickly. Immediately add the bonito flakes--no need to stir. Allow the flakes to settle on the bottom of the pot (30 seconds to 1 minute). Filter through a fine meshed strainer or a cheesecloth-lined sieve. You must remove the bonito flakes promptly; if the bonito flakes boil for more then a minute, then the stock will become too strong and bitter and isn't suitable for use in clear soups (though it can be used as a base for thick soups, in simmered foods, etc).

This is called primary dashi since it is the first extraction from the kelp and bonito. You can reserve the bonito flakes and kelp for secondary dashi (recipe not listed here, but it is in Shizuo Tsuji's book) if you like, but it should only be used for as a base for thick soups or simmering foods or things like that since it will be much weaker and not have as pure of a flavor.

Hiroko Shimbo says in "The Japanese Kitchen" that the dashi can be refrigerated for up to four days tightly covered, or can be frozen for longer term storage.