Tuna salad sandwiches are so yummy but tend to be mushy (and boring!) when picked up from the corner market. Separate the ingredients for the perfect sandwich that's also healthy! Lighten your lunch, and mix Greek yogurt with one can of drained tuna. Add a touch of grainy-style mustard and a squeeze of lemon to the tuna salad, and then nestle in a few leaves of butter leaf lettuce. Top with a few slices of cucumber, tuck it all in whole wheat bread, and you have the makings of the perfect tuna sandwich. Fresh green grapes finish the lunch with a pop of flavor.