Mix one 6 1/2ounce can water-pack tuna, drained; 1/3 cup cream-style cottage cheese; 1/3 cup chopped celery; 1 tablespoon chopped sweet pickle; 1 tablespoon chopped onion; 1 tablespoon low-calorie mayonnaise-type dressing; and 1/4 teaspoon salt.
Spread 4 slices rye bread with 4 teaspoons low-calorie mayonnaise-type dressing.
Top each slice with lettuce leaf and 1 slice tomato.
Sprinkle with salt.
Spoon tuna mixture atop tomatoes.