One good recipe for tuna melts is the simple tuna melt recipe from Allrecipes. Food.com's open-faced version of a tuna melt is also a good recipe, and offers a slightly more sophisticated take on the classic dish.
The simple tuna melt recipe from Allrecipes is made using one small can of tuna, 2 tablespoons of mayonnaise, 1 teaspoon each of Dijon mustard and balsamic vinegar and 2 teaspoons of chopped dill pickle. This mixture is placed on top of a toasted slice of bread, and 1/4 cup of shredded sharp cheddar is placed on a second toasted slice. The slices are baked for about seven minutes in a 375 degree oven then put together, sliced into halves and served hot. This recipe makes one sandwich.
The open-faced melt serves four and calls for two cans of tuna, 1/4 cup of mayonnaise and 1-2 tablespoons of lemon juice or balsamic vinegar. These ingredients are combined with a celery rib and two fresh green onions, both finely chopped, as well as some chopped parsley and seasonings to taste. This mixture is then spooned on to the top of four slices of toasted rye or pumpernickel bread. Then, Swiss or mozzarella cheese slices are layered with tomato slices on top of the tuna mixture. The sandwiches are placed under a broiler for a few minutes until the cheese is melted.