A melt sandwich (also known in Australia, New Zealand, and the United Kingdom as a toasted cheese sandwich or, toastie) is a type of sandwich containing bread and some type of filling that is seasoned with cheese, sometimes grated. The sandwich is then grilled or fried until the cheese is melted. It may be served as an open face sandwich or a closed face one.One common filling is tuna fish, with mayonnaise; the result would then be a tuna melt sandwich.