8 oz. baby bella mushrooms, sliced
8 oz. white button mushrooms, sliced
4 tsp. salt, divided
2 Tbsp. butter
1 large white onion, diced
4 celery stalks, ends trimmed, diced
3 medium carrots, diced
3 garlic cloves, minced
1 cup wild rice
1 tsp. dried thyme
2 Tbsp. balsamic vinegar
1 Tbsp. Worcestershire sauce
3 cups beef broth
1 cup half and half
Freshly shredded Parmesan cheese, for serving
Add baby bella mushrooms and sprinkle with 1 teaspoon salt. Stir to coat and cook, stirring occasionally, until mushrooms have released their natural moisture, it has evaporated and mushrooms are browned. Remove mushrooms from pot and set aside. Repeat the browning process with another 2 teaspoons of olive oil, button mushrooms and 1 teaspoon salt. Remove from pot and set aside.
Add the final teaspoon of oil to the pot, along with the salted butter. Add onion, celery, carrot, and final teaspoon salt, stirring to coat. Cook, stirring occasionally, until vegetables have begun to soften, about 5 minutes. If necessary, add a splash of stock to deglaze the pot and get the browned bits off the bottom. Stir in garlic, cooking until fragrant, about 1 minute more.
Add wild rice. Then, stir in thyme, balsamic vinegar and Worcestershire sauce. Stir in beef stock and bring mixture to a boil. Cover and simmer 40-60 minutes, or until rice is tender and has absorbed most of the liquid. Stir in half and half and reserved mushrooms. Top with freshly grated Parmesan cheese to serve.
For a thicker soup, make a cornstarch/water slurry and and thicken before serving.