- 1 (5- to 6-inch) piecekombu (dried kelp)
- 5 cups cold water
- 2 (5-g) packages katsuo bushi (dried bonito flakes; 1 cup)
- Special equipment: cheesecloth
- Wipe any sand or salt from kombu with a dampened cloth. Bring kombu and water just to a boil in a 3-quart saucepan over high heat. Remove kombu with tongs and reserve for another use.
- Sprinkle katsuo bushi over liquid and remove pan from heat. Let stand 3 minutes, then pour through a cheesecloth-lined sieve into a bowl.