1 1/2 lbs. hamburger
2 tbsp. onion, chopped
2 tbsp. mayonnaise
8 oz. Mozzarella cheese
1 pkg. taco seasoning
1 can tomato soup

Brown meat and onion, drain. Sprinkle taco seasoning on, stir and simmer 10 minutes. Combine remaining ingredients in bowl; mixing cheese in last and refrigerate for at least 30 minutes. Spread on hamburger bun halves and bake at 300 degrees on a cookie sheet for 20 to 25 minutes.

Serves 8 to 10.