Dashi, a Japanese fish-based soup stock, is extremely simple to make at home. Since dashi is a critical ingredient for a lot of Japanese cooking, and the crispy mixed rice recipe I just posted uses dashi, I thought I'd post a dashi recipe (from Yamaoka 1984).
4 1/2 cups water
2 cups bonito flakes (hana-katsuo)
3-inch piece kelp (konbu)
1) Pat the kelp with a moist towel (but do not wash), and cut 1/2-inch slits into the kelp every inch or so.
2) Add all the ingredients to a pot, bring to a boil over medium heat, and simmer for 5 minutes.
3) Strain the kelp and bonito flakes out of the stock (we use a wire mesh strainer; you can line the strainer with cheesecloth for a clearer stock).
Asian markets usually carry bonito flakes and konbu; both are typically packaged in plastic bags, and neither requires refrigeration.
Yamaoka calls this niban dashi (secondary bonito stock).
Yamaoka, Masako. 1984. A First Book of Japanese Cooking: Family-style food for the home. Kodansha International, Tokyo.