In a large pot, heat the olive oil over medium heat. Add the chopped onion, garlic, carrots, and celery. Sauté until the vegetables are softened, about 5-7 minutes.

Add the sliced mushrooms and cook until they release their moisture and begin to brown, about 5 minutes.

Stir in the wild rice and vegetable broth. Bring to a boil, then reduce heat to low and simmer for about 30-35 minutes, or until the rice is tender.

Once the rice is cooked, stir in the heavy cream, thyme, soy sauce, salt, and pepper. Cook for an additional 5 minutes to heat through.

If desired, blend a portion of the soup for a creamier texture, then stir back into the pot.

Serve hot, garnished with fresh herbs if desired.