What is mushroom soup?

Mushroom soup is a soup made with mushrooms as a primary ingredient. It can be prepared in a variety of ways, but typically involves sautéing mushrooms in butter or olive oil, then simmering them in broth or water with other ingredients such as onions, celery, carrots, garlic, and herbs. The soup may be thickened with flour or cornstarch, and is often served with cream, sour cream, or yogurt. Mushroom soup can be made with any type of mushroom, but some of the most commonly used varieties include white button mushrooms, cremini mushrooms, and portobello mushrooms. It can be served hot or cold, and is a popular dish for both casual and formal occasions.