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Miso Soup with Sweet Potato, Shiso, and Shimeji Mushrooms

This easy, homey miso soup combines sweet potato, fresh shiso, and shimeji mushrooms for a comforting and attractive variation on this Japanese classic. Rich and satisfying with a minimal amount of fuss.
This recipe is naturally gluten-free, dairy free, and nightshade-free. It is also easily adaptable to being vegan.
Prep Time10 minutes
Cook Time20 minutes
Dashi prep time15 minutes
Total Time45 minutes
Course: Main Course, Side Dish, Soup
Cuisine: Japanese
Servings: 6
Author: Gastricurious

Ingredients

For the Dashi:

  • 6 cups water
  • 1 6" piece dashi kombu (dried kelp for dashi)
  • ΒΌ cup bonito flakes (katsuobushi)

For the Soup:

  • 1 medium sweet potato
  • 3.5 oz shimeji mushroom cluster
  • 10 shiso leaves
  • 2 Tbs white miso

Instructions

To make the dashi:

  • Clean the kombu by gently wiping it with a clean, damp cloth or paper towel. Add it to a large soup or stock pot along with the water. Set heat to medium, and watch carefully as the water approaches boil. As soon as it hits the boiling point, remove the kelp (it can be discarded or else saved for another recipe).
  • Add the bonito flakes to the pot and boil until they no longer float (about 5 minutes). Strain broth through cheese cloth or a fine mesh strainer. Reserve broth. Bonito may be discarded or saved for use in another recipe.
  • Dashi can be made up to three days in advance. Keep refrigerated until ready to use.

To make the miso soup:

  • Cut the sweet potato into bite-sized chunks (skin may be left on). Slice the base off of the mushroom cluster to remove the culture medium. Separate the mushrooms by hand, leaving some in small clusters of 2 to 5. Slice the shiso into thin strips.
  • Return dashi to the pot and bring to a simmer. Add sweet potatoes and shimeji and simmer for 10 minutes.
  • Add shiso and simmer 5-10 minutes longer, or until all vegetables are tender.
  • Turn off the heat. Stir in the miso until fully dissolved. Ladle into bowls and serve.

Notes

  • Don't confuse the small containers of miso paste (aka "instant miso") that you may find in the Asian section of some supermarkets for pure miso. True miso will be kept in the refrigerated section, and is sold in tubs or bags.
  • We prefer white (shiro) miso for our miso soup. Other varieties, like red miso, will also work, but have a stronger flavor.
  • Kombu (also spelled konbu) can be found in most Asian markets or online. There is a tremendous array of different grades of kombu available, with an equally varied array of uses and prices. You will want to look for a variety labelled as "dashi kombu", which should be readily available and among the least expensive options.
  • Shimeji mushrooms (also called beech or clamshell), are commonly available in Asian markets and at many grocery stores that stock "exotic" or "gourmet" mushrooms (such as Whole Foods). If you cannot find them, shiitake mushrooms will also work in this recipe (albeit with a slightly different flavor).
  • We use common orange sweet potatoes in this soup because we like the color they add to the presentation. You could also use the white-fleshed Japanese variety if you prefer.
  • Shiso (a variety of perilla) is an herb used extensively in Japanese cooking. Look for it in Asian markets, especially dedicated Japanese markets like Mitsuwa. A related plant can be found at markets geared more towards Korean food under the name "sesame leaf" (which is another type of perilla, and not related to sesame at all). It has a different, stronger flavor from shiso. We haven't tried it in this yet, so you are on your own if you want to make that substitution.