The leftover mushrooms and kombu kelp can be reused once to make a second batch of dashi. Keep the leftover pieces in a covered container in the refrigerator for up to 3 days. To prepare a second dashi with the leftovers, skip soaking the mushrooms and use fresh water.

Prep Time: 5 minutes
Cook Time: 5 minutes

Makes about 2½ cups (625 ml)

3 cups (750 ml) cool water
2 oz (50 g) dried shiitake mushrooms
One 2 x 2-in (5 x 5-cm) piece kombu kelp

Cover the dried shiitake mushrooms with the water and allow to soak for 5 minutes. Drain the mushrooms, reserving 2½ cups (625 ml) of the soaking water.
Wipe the kombu on both sides with a damp cloth. Bring the reserved shiitake water to a boil in a saucepan. Remove from heat and add the kombu and soaked mushrooms.
Stir all ingredients, and then allow to sit for 5 minutes. Strain away mushrooms and kombu to obtain the dashi liquid.
Soak the mushrooms for 5 minutes.
Wipe the kombu with a damp cloth.
Add kombu and mushrooms to hot water.
Strain the liquid.