Butter or spray cooking pan, and place whole wheat bread and cheese slice in pan.

Stove should be on low heat, while it cooks combine chicken salad, mayonnaise, onion, and sweet relish in a bowl.

When cheese is melted or bread is grilled to liking. Grill other slice of bread while you assemble chicken salad mixture on the grilled cheese toast. Add dijon mustard, lettuce, and second slice of bread.