Mika's French Onion Soup

3 large onions, sliced, separated into rings

2 Tbsp butter or margarine

2 cans (10-1/2 oz. each) condensed beef broth

1 Tbsp Steak Sauce

1 cup seasoned croutons

1 cup Shredded Mozzarella Cheese

Cook onions in butter in large saucepan on medium heat 10 min. or until golden brown, stirring frequently.
Add broth, 2 soup cans water and steak sauce. Bring to boil. Simmer on medium-low heat 5 min.
Heat broiler. Ladle soup into 4 large ovenproof bowls; top with croutons and cheese. Broil 2 to 3 min. or until cheese is melted.