For 92 years (and counting!), my baachan (Japanese grandmother) has been making this soup. She raised four beautiful daughters through World War II — so she knows a little something about comfort food. My big sis and I sought out baachan's recipe, which is nothing like your watered-down sushi bar miso. This is hearty, comforting, and as authentic as Japanese food gets.
See all miso recipes.
*Note: Kombu is a type of seaweed used for stock. Look for it in Asian specialty stores or online.
In a bowl, soak the dried mushrooms in warm water for 10 minutes. Drain and reserve the liquid. Add the potatoes to 4 cups water in a large pot and bring the water to a boil.
Once the potatoes are almost fork-tender, reduce the heat to a low simmer. Add the stock, kombu, onion, carrot, tofu, and wakame.
Add both types of miso paste and mash them into the soup until thoroughly dissolved. Serve garnished with the scallions.