This is highly recommended!
Here is the recipe in case the original goes missing.
Skinny Tuna Melt
src - Skinny Taste
Combine tuna, celery, carrots, onion, mayonnaise, vinegar, salt and pepper.
Heat a large skillet over low heat. Spray skillet with oil, and place two slices of bread on top. Top bread with cheese, then tuna salad and tomato. Cook on low heat until cheese melts and bread gets toasty. Serve immediately.