- 2 (4-inch) square pieces of kombu (edible kelp, also called dasima or haidai)
- 2 1/2 quarters of water
- 2 cups bonito flakes (dried, fermented skipjack tuna; also known as katsuiobushi)
Fill a 4-quart saucepan with water and soak kombu in it for 45 minutes.
Set the saucepan over medium-high heat until the water reaches 155°F. It should take about 10 minutes.
Carefully remove the kombu from the pan and increase the heat to high. Bring to a boil and then reduce to simmer.
Add the bonito flakes and simmer for about 10 minutes.
Strain the liquid through a cheesecloth into an airtight container.
Use this liquid as the base for miso soup, udon soup or to add umami (savory) flavor to any dish you like.