Update: There is now a very detailed step-by-step lesson for making dashi here . It’s highly recommended if you are a dashi making newbie.
Dashi is the basic soup stock used in Japanese cooking. Unlike Western or Chinese basic stocks that rely on stewing meat or vegetables for a long time to extract the flavors, Japanese dashi can be quite quickly made. There are instant dashi granules available, but like instant stock cubes they are high in sodium and stuff. Not that sodium is necessarily bad, but when it’s so easy to make a real stock from scratch, why go for the fake stuff?
There are basic ingredients for making dashi, all of which can be bought at a Japanese grocery store. Korean or general Asian/Chinese grocery stores may have them too, though I have noticed that while instant dashi is readily available, the basic dashi ingredients aren’t always. You may be able to buy bonito flakes and konbu seaweed at a Whole Food or very well stocked regular supermarket also these days too. Some natural food stores sell these ingredients sometimes.
The first ingredient used for dashi is shaved dried bonito flakes, called katsuo bushi or kezuri bushi. You can also buy a whole, dried bonito (it looks like a fish-shaped wooden log) and shave it on something that looks like a plane, but this is too much work for me. I just use the preshaved bonito flakes that come in big bags.
Dried kombu seaweed is the second ingredient. This is a leathery seaweed, that comes in large leaves. What I do is to cut up the leaves with scissors into approximately 4 inch lengths, pack them well in multiple layers of plastic bags and store them in the freezer.
The third commonly used ngredient is dried sardines, called niboshi. This produces the most distinctively flavored stock. I rarely use niboshi myself, simply because it’s rather hard to get a hold of good, non-rancid niboshi here where I live. If you have some niboshi, sniff it. If it smells strange, your stock will taste strange too. Cats love niboshi, either dried or after they’ve been used for stock.
Following my mother’s example, I usually make a dashi using bonito flakes and kombu. This is also called ichiban-dashi - first stock. Frugal housewives often make niban-dashi - second stock - by re-extracting more goodness out of the kombu and bonito flakes already used for ichiban-dashi. Niban-dashi is fine to use for stewed vegetables and the like.
Soak the dried kombu seaweed piece in 3-4 cups of cold water for about 20 minutes. Bring the water to the boil, then add the handful of bonito flakes. Immediately switch off the heat and let it sit for at least 5 minutes. Strain through a sieve, pressing out all the goodness.
Makes 3-4 cups.
When I’m pressed for time, I use the mizudashi method of making dashi. This is the method I’ve described for making vegetarian dashi , except that I add some bonito flakes. I put a piece of kombu seaweed and a big handful of bonito flakes in a jug of cold water, and let it steep for at least a few hours or overnight. To use the dashi I simply strain it out. The dashi keeps in the fridge for a few days, and if I don’t use it up during that time (which is rare) I just freeze it. Aside from having to remember to fill up a jug, this method couldn’t be easier.
The two methods described above make ichiban dashi (first dashi), which is the strongest in flavor. This is used for dishes where the dashi flavor is paramount, such as soups or dipping sauces. But for stews and other dishes where dashi is more of a background component, a frugal cook uses niban dashi (second dashi). Since kombu and bonito flakes are so expensive outside of Japan, it really pays for those of us who live ‘over the sea’ to make niban dashi! To make this, simply re-simmer the kombu and bonito flakes you used for making ichiban dashi for a while; this extracts a light flavored dashi. I freeze the kombu-bonito flakes clumps and use a couple of them at a time to make niban dashi.