So, i know this is not the most original idea, but it's pretty good and satisfying...
1/2 can Tuna (i prefer, solid white Albacore in water)
1-2 Tbs Mayo
2 Tbs chopped celery
2 tsp chopped green onions
salt and pepper to taste
Romaine lettuce leaves
Vine ripe tomatoes
Combine Tuna, mayo, celery, onions, salt and pepper in a small bowl. Stir. Place tuna mixture on washed and dried lettuce leaves, garnish with tomato and more salt and pepper, if desired. You could also add your choice of cheese. Delicious!