Dashi (wikipedia definition) is a type of Japanese soup stock; one of the most well known uses of dashi is as the base that you add miso paste to make miso soup, however dashi is also used in many other applications in Japanese cooking, similar to how French cooking uses stock.
Dashi is extremely easy and quick to make. All you need to do is measure out ingredients, boil water, and strain. It is made from just three ingredients: konbu (giant kelp), katsuobushi (dried bonito flakes), and water. Quantities for these ingredients are given in the recipe below; however once you have made dashi a few times, you can eyeball the quantities since it isn't necessary to use exact quantities. In fact, if you compare various recipes for dashi, you'll notice that they often differ from each other in the amounts and ratios of konbu and bonito flakes used--I've seen recipes which use nearly twice as much konbu and bonito flakes and ones that use only half as much as my recipe below; you can adjust the amount you use depending on the strength of the broth that you'd like. In the recipe below, a range is specified for the quantities of bonito flakes and dashi; the smaller amounts are from Hiroko Shimbo's recipe and the larger quantities is from Shizuo Tsuji's recipe.
This is called primary dashi since it is the first extraction from the kelp and bonito. You can reserve the discarded bonito flakes and kelp for secondary dashi (recipe not listed here, but it is in Shizuo Tsuji's book) if you like, though secondary dashi 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 it will not have as pure of a flavor.
You can also make vegetarian kelp broth, called konbu dashi, (which can be used as a vegetarian replacement for dashi) by following the steps to extract the kelp flavor and and stopping just before the bonito is added. Kelp broth can also be used as a replacement for vegetable both in non-Japanese dishes; it helps to give the dish umami.
Good quality kombu will be covered on the surface with a fine white powdery substance. Don't wash the white powder off of the konbu; it is part of what becomes the flavor the stock. Most kombu today is cleaned before being sold, so it is isn't necessary to wipe it and can be used as is, unless you can see visible dirt on it. (If you do need to wipe it, be careful to not wipe off much of the white powder.) Konbu contributes glutamic acid to the stock, which is responsible for umami (wikipedia). Soaking it in water overnight helps to extra the most flavor; however if you are pressed for time, you can extract sufficient flavor by skipping the soaking step and placing the kelp in water that you slowly bring to a boil.
Fresh, good quality pre-shaved katsuobushi will be fluffy and yellowish-beige colored with a hint of blush pink.
Konbu stores well over long periods of time, however bonito flakes lose flavor once the package is opened so they should be used up soon after the package is opened; often I will make a double or triple batch of dashi in order to use the entire package of bonito flakes (packages usually contain 50 to 100 grams), and then I freeze most of it in ice cube trays so that it is easy to use in recipes.
Recipe: Based on "Fish Stock Preparation (Dashi)" from "The Sushi Experience" by Hiroko Shimbo and "Primary Dashi" from "Japanese Cooking: A Simple Art" by Shizuo Tsuji.
Rating: Great. Quick and easy. This is even easier to make than chicken stock.
Status: Made many times.
Ingredients (makes 1 quart):
- 1 quart (4 cups) cold water
- 1/2 oz (about 15 grams) to 30 g (about 1 oz) konbu (kelp, sometimes also spelled as kombu) *
- 2/3 oz (about 20 grams, or 2 cups lightly packed) to about 1 oz (30 g) katsuobushi (dried bonito flakes) *
(Optional) To extra the most flavor from the konbu, soak the konbu in 1 quart of cold water overnight (about 10 hours).
Slowly bring the kelp and in its soaking water to a boil (use fresh water if you didn't soak the kelp overnight) , uncovered, so that it reaches the boiling point in about 10 minutes. 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. 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. Remove the kelp just before the water boils; kelp emits a strong odor if boiled that will overpower the stock. This stock is what is called konbu dashi (kelp stock) and can be used in vegetarian or vegan recipes as a replacement for dashi.
To turn the konbu dashi into dashi, allow the water to come to a boil, and then add the bonito fish flakes. Count 10 seconds, and then turn off the heat. The fish flakes should start to sink almost immediately (they may not sink all the way to the bottom). Let the stock rest with the fish flakes about 2 minutes and no more than 3 or 4 minutes. During this time remove any foam or scum that rises since it can affect the flavor. Immediately pour through fine meshed strainer (chinoise), cheesecloth-lined sieve, or a strainer lined with a wet paper towel. Don't squeeze the bonito flakes. Remove the bonito flakes promptly; if the bonito flakes boil or soak in the stock for more then a couple minutes, then the stock will become too strong, bitter, and "fishy" tasting and isn't suitable for use in clear soups (though it can be used as a base for thick soups, in simmered foods, etc).
To make the stock even clearer, let the dashi sit undisturbed for at least 10 minutes. The fine particles will fall to the bottom. Being careful to disturb the liquid as little as possible (so that you don't raise up the sediment), spoon all of the dashi from the top of the bowl into a clean bowl, except for the few tablespoons of dashi at the bottom with lots of sediment. Discard the sediment filled remainder of dashi.
Dashi can be refrigerated for up to four days tightly covered.
Dashi can be frozen for longer term storage, however freezing will cause a loss in quality (usually the smokiness imparted by the bonito flakes diminishes) though frozen dashi is superior to "instant" dashi mixes since these often have preservatives. Frozen dashi is suitable for cooking (especially in recipes that only use a few tablespoons), but since its delicate flavors are diminished, miso or dashi based soups are best when made with fresh dashi (though frozen can be used in a pinch). Since many Japanese recipes call for a small amount of dashi, I often freeze some dashi in an ice cube tray since this makes it easy to melt a few ice cubes when needed; this makes meal preparation quicker, especially on busy nights. To defrost, gently heat until it melts or allow to defrost in the refrigerator on on the countertop.
If you want an extra smokey broth, then you can either use thicker katsuobushi flakes, or once the dashi is cool, you can reheat it to a simmer, and immerse another few handfuls of katsuobushi flakes and strain as in the proceeding recipe.