I’ve been using dashi crystals in most of my Japanese cooking, because I thought it was easier, and because the ingredients for real dashi are so hard to find. Turns out, Huckleberry’s, our locally smug organic supermarket, carries both katsuobushi tuna flakes and kombu seaweed. You could probably find them at Trader Joe’s, or any similar store or Asian market.
Kombu seaweed comes in shards, like broken plastic. It rehydrates to something that looks and feels like it came off a wetsuit. Katsuobushi is skipjack tuna, dried and shaved. It looks like, well, dried wood shavings. They are both dried products, so they keep essentially forever (although the tuna should probably be used up soon after opening). My recipe is an amalgam of several I’ve come across, and couldn’t be simpler.
1. Take a 2″ square of kombu, rinse and wipe. Place in a quart container of water.
2. Add a grab handful of katsuboshi, call it a loose half a cup. Some recipes call for more.
3. Place in the refrigerator overnight.
4. Next morning, heat it in a saucepan until just steaming, then strain out the solids, and et voilà, as the Japanese chefs would say, you have dashi. If you want something more instant, skip the overnight part.
A more traditional way is to soak only the kombu overnight. You leave out the katsuboshi until the water is steaming, then remove the kombu, bring to a boil, add the katsuboshi, let cool, and strain. For a simpler, vegetarian dashi, just leave out the katsuboshi altogether.
The Japanese will also use the strained solids to make a second, weaker, infusion of dashi. Or, the soggy katsuboshi can be added to oatmeal, to rice, to an omelet, anywhere you would use a tablespoon or so of tuna. The kombu is edible, but I am told that dashi kombu is older and tougher than snacking kombu. You can guess the experience just by feeling it and looking at it: It tastes vaguely seafoodish, and feels like you are biting through rubber. Both are useful additions to a compost pile.