Mushroom Soup

Ingredients

• 1 lb mushroom, washed and quartered
• 1 large yellow sweet onion, chopped
• 3 carrots, washed and sliced
• 2 large celery ribs, sliced
• 1 tablespoon thyme
• 6 cups beef stock (or 6 cups water with 6 beef bouillon cubes)
• 1 slice butter
• 2 tablespoons cooking sherry