1 (7 or 9 oz.) can white (not light) tuna
3 oz. Swiss cheese
1/4 c. mayonnaise or salad dressing
2 tbsp. chopped onion
1 tsp. lemon juice
1/2 tsp. salt

Drain and flake tuna, add cheese, cut into 1/4" cubes. Combine with mayonnaise, onion, lemon juice and salt. Spread on buttered hamburger buns, wrap in foil and bake for 20 minutes at 350 degrees. Makes for 6 to 8.