- 2 tablespoon oil*
- 2 tablespoon vegan butter*
- 4 medium yellow onions, peeled + sliced into slightly larger than 1/4-inch rounds
- 1 teaspoon salt
- 1 teaspoon black pepper
- 4-6 cloves garlic, minced
- 2 cups thinly sliced fresh shiitake mushrooms (or use dehydrated mushrooms)*
- 2 tablespoon arrowroot starch or cornstarch (or all purpose flour if not gluten-free)
- 4 bay leaves
- 3 teaspoon fresh thyme leaves, chopped (or sub 1 1/2 teaspoon dried thyme)
- 8 cups vegetable broth or water
- 2 tablespoon coconut aminos or 1 tablespoon tamari since it is saltier
- 2 tsp miso paste (if soy-free, use chickpea miso)
Heat a large pot over medium heat. Once hot, add oil/butter, or water and the sliced onions (they should be ~1/4 inch thick so the soup has nice texture). Stir and cover.
Cook the onions over medium heat for 3-4 minutes or until they start to very slightly brown. Then turn heat to low and cook for 40 minutes, opening the lid and stirring every 5 minutes. The goal is to slowly caramelize the onions is to cook.
Be careful not to burn by keeping heat on low and adding a bit of water or broth as needed to prevent sticking.
Add salt and pepper while sautéing, plus more to taste later as you season the soup.
When your onions are close to being caramelized, add minced garlic and mushrooms and sauté for 2-3 minutes more. Then add starch/flour (optional, for slight thickness) and stir to fully combine (it should absorb fully into the onion mixture).
Add bay leaf, thyme, vegetable broth, and coconut aminos.
Cover and simmer soup for about 20 minutes to develop and meld the flavors. Then simmer uncovered for another 5-10 minutes so it thickens slightly (the flavors will intensify even more). Do not let the soup boil.
To incorporate the miso, add it separately to a small dish and top with ~1/4 cup of the warm broth. Use a spoon or whisk to fully mix. Then add back to the pot and turn off heat minimize the amount of heat to the miso so that the probiotic benefits remain. Stir to combine.
Taste and adjust flavors as needed, adding more salt or pepper to taste, coconut aminos for depth of flavor, or miso for umami flavor.
Serve hot topped with croutons and additional herbs and black pepper. Store cooled leftovers in the refrigerator up to 4 days, or in the freezer for up to 1 month.
For an oil free recipe, use 1/2 cup of water, plus more as needed to prevent sticking. Add 1 tablespoon of water more at a time as needed to prevent sticking/ burning.
Mushrooms are optional, but they add a nice rich flavor and a nice texture to make the soup heartier.