Homemade Vegan Miso Soup

I recently made a discovery that I'm exited to share with everyone: Kombu. Kombu is a dried seaweed from Japan that is used to make dashi, the savory broth that forms the base of miso soup and other classic Japanese soups. Often it is combined with dried, fermented bonito fish flakes, other dried fishes, or dried shitake mushrooms, which I used in this recipe. Kombu is special for a couple of reasons. First, it's a great source of iodine, which is important for thyroid heath. Second, it contains natural glutamic acid, an amino acid present in meat and other proteins that is responsible for umami, what the Japanese call savoriness.

Umami is the reason meat tastes so rich and delicious, and the reason why monosodium glutamate (MSG) is such a widely used flavoring.  Finding a natural, healthful, vegan source of umami like kombu is really exciting because it means you can make vegetarian soups, even traditionally meat-based ones like French onion, that have a similar, deliciously savory quality to the original recipes.

I've started using Kombu as a base for stock in all my vegetarian broths. Canned and cartonned vegetable broth is generally pretty icky; it tends to taste like salty, dirty water. And the longer you simmer kombu, the more savory, more neutral, and less like seaweed your broth tastes. This means that you can use it in delicate soups, and they won't be overpowered by an oceany flavor.

I wanted to start with a basic kombu and shiitake mushroom dashi for a Japanese miso soup, because it's an easy, traditional way to get familiar with kombu. And miso is in itself quite healthful. Like yogurt, it's a fermented probiotic with live bacterial cultures; never boil miso soup, or you'll kill those good bacteria. This time of year, you can garnish your miso with all the beautiful fresh baby greens and spring onions that are at the farmers market right now.

For 2.5 to 3 cups of soup, enough for 2 people as a light entree and 4 people as a small starter, you will need:

  • 8 dried shiitake mushrooms (Definitely use dried here - fresh won't give you the same pungent flavor.)
  • A large, 10"x3" piece of kombu dried seaweed, rinsed well (Kombu, like dried shiitakes, is available in Asian supermarkets. Kombu looks like a piece of stiff black shoe leather. It may have a light white powder on it - this isn't mold, it's dried seawater.)
  • 2 to 3 tablespoons white miso paste (I prefer the flavor of white to red miso - it's sweeter and more delicate - but you can use red if you like. Miso paste is widely available in many supermarkets in the refrigerated dairy section. It is made from fermented soybeans and wheat. If you are gluten-free, health food stores, Whole Foods, and Asian markets have gluten-free options.)
  • Water

Garnish Options: 

  • Cubed silken or firm tofu
  • Spinach
  • Arugula
  • Watercress
  • Baby mustard greens or kale
  • Rehydrated wakame seaweed or shredded nori
  • Shredded carrots
  • Thinly sliced scallions
  • Cooked udon or soba noodles

Directions:

Pour 2 cups of boiling water over the dried shiitakes and allow to soak for 30 minutes.

Meanwhile, cut the kombu into small pieces and simmer in a large saucepan with 4 cups of water for about 30 minutes. 

Remove the mushrooms from their soaking liquid, reserving the liquid. Discarding the stems, thinly slice the shiitakes, and add to the kombu broth. (I found I only needed to slice 4 of the 8 mushrooms for this amount of soup.) Now pour the soaking liquid into the kombu broth, making sure hold back the gritty mushroom sediment that collects at the bottom. Remove the kombu pieces from the broth. (They are edible, but I'm not fond of the texture.) Take the pan off the heat and stir in the miso paste to taste and any garnishes. Return the pan to the heat and bring it to just under a boil - boiling will kill the healthy, probiotic bacteria in the miso. Serve immediately.