Begin by lathering one piece of the rye bread with mayonnaise. Next top with the tuna salad. Finish by topping with the cheese.Heat half the oil in a skillet. Once warm, add the sandwich and cook for 2 - 3 minutes to get a good crisp. Before flipping, pour the oil over the top piece of rye bread. Flip the sandwich over and cook for another 2 - 3 minutes. Put a lid on the skillet to help get a good melt on the cheese.To serve, cut in half. Enjoy!