Tavern Burgers

1 pound ground beef
1 small onion, diced
1 cup chicken gumbo soup
2 tablespoons water
3 tablespoons mayonnaise
3 tablespoons mustard
1/4 cup catsup

Brown meat and onion. Add soup and water. Simmer 15 minutes. Mix remaining ingredients and add to meat mixture. Simmer 5 minutes longer.

Serve over heated hamburger buns.