2 1/2 c. sliced onions
3 tbsp. butter
3/4 lbs. mushrooms, sliced thin
2 tbsp. white vinegar
Salt & pepper to taste
1 tbsp. instant beef bouillon
2 (14 1/2 oz.) cans beef broth
4 slices French bread, 1/2" thick
1 c. grated Parmesan cheese
1/4 c. grated Parmesan cheese

In a 3 quart saucepan over medium heat, saute onions in butter for 5 minutes. Add mushrooms. Cook and stir three minutes. Add the next four ingredients (white vinegar, salt and pepper, instant beef bouillon and beef broth), bring to a simmer, stirring constantly. Simmer for 10 minutes. Preheat oven to 400 degrees. Place bread on baking sheet, toast until slightly browned. Remove toast; heat broiler. Divide soup equally into 4 (1 1/2 cups) oven proof bowls. Top each serving with one slice of toast, 1/4 cup Swiss cheese and 1 tablespoon Parmesan cheese. Broil 3 to 5 minutes until golden brown. Makes 4 servings.