Preparation -
Slice onion into 1/4 inch slices and saute in a small amount of butter or margerine just until lightly browned and barely softened.

Slice rolls and place on a baking sheet. On one side of roll, place a generous portion of tuna salad. Top with a slice of sauteed onion. Top with a slice of swiss cheese. Spread other side of roll with butter or margerine.

Place in oven at least 8" to 10" below broiler. Set oven to broil. Broil 3 to 5 minutes or just until buttered side of roll is lightly browned and cheese is melted.