Kombu Dashi

Recipe 10 min Preparation Time 45 min to up to overnight Cooking Time

Kombu Dashi

10 min Preparation Time 45 min to up to overnight Cooking Time

About this Recipe

Dashi, traditionally made with smoked cured bonito (skipjack) and sun-dried giant kelp, provides a foundation for flavor in Japanese cooking. This vegan version is prepared with only kelp, or kombu. Some of the best-quality kombu — with wavy fronds that dry to a dark amber or green-black color — is harvested in northern Japan in the subarctic, mineral-rich waters around Hokkaido. Kombu used for dashi typically is grown for two years and harvested during the summer months, its fronds laid out to dry in the sun then shaped and folded for packaging. Several types of kombu, from different parts of Hokkaido, are commonly used for dashi, including ma kombu, hidaka kombu, rishiri kombu, and rausu kombu. Each has its own character-giving properties, some more salty or sweet or especially good for making a clear broth. Kombu contains naturally occurring glutamate, aka umami, and easily imparts flavor and nutrients to clear water.

The Benefits

Kombu is high in iodine, which supports thryroid function, and iron, which assists in getting oxygen delivered to your cells. It’s also a good source of calcium, particularly for those who don’t consume dairy products. Shiitake mushrooms add fiber, along with B vitamins.

Note: Dried shiitake mushroom is optional. Because of the dried mushroom’s strong flavor, you need only one or two, so that the taste of kelp comes through too. Best-quality dried shiitake are expensive. Look for thick mushroom caps that have deep, light-colored cracks.

Ingredients

Makes 1 quart (1 L)

1 oz (30 g) kombu, wiped with a clean, dry cloth (don’t rinse the kombu)
1 qt (1 L) cold filtered water
1 or 2 dried shiitake mushrooms (optional), cleaned with a dry pastry brush

Directions

Step 1

Cold-brew method: Using scissors, cut the kombu, if necessary, so that it fits in your bowl or container (large enough to hold the water). Add the shiitake, if using. Cover with water and let stand at room temperature for 8 hours or overnight. Remove the kelp and reserve for use in other recipes. Remove the shiitake mushroom, squeezing out any excess liquid; you can use the rehydrated shiitake as you would fresh shiitake (just cut off and discard the tough stem). Pour the dashi through a fine-mesh sieve to strain.
Step 2

Stovetop method: Using scissors, cut the kombu, if necessary, to fit in a heavy-bottom pot. Put the kombu and shiitake mushroom, if using, in the pot and pour in the cold water. Turn the heat on low. You want to gently simmer (not boil) it so that you have a clear broth. Let it simmer at a low temperature (about 150˚F/65°C) for 45 minutes to 1 hour. If using shiitake, remove it after 15 minutes; you can use the rehydrated shiitake as you would a fresh one (just cut off and discard the tough stem). Remove the kelp and reserve for use in other recipes. Strain the dashi through a fine-mesh sieve.
Step 3

Use the dashi immediately or store it, covered, in the refrigerator for up to 3 days.

Try It With: Make miso soup, hot pot, simmer vegetables in it, or use it as you would vegetable broth

Zero Waste: Use the leftover kelp to make a seaweed fertilizer tea for spraying or watering your plants by soaking it in water for a few weeks

About the author

Betty Hallock

Betty is a writer and editor: A journalist who formerly worked at the Wall Street Journal, Los Angeles Times, and Los Angeles magazine, she also has co-authored four cookbooks. Her favorite meal for as long as she can remember has been ochazuke — rice with tea and pickled plum.

View profile