1/2 tsp. fresh lemon juice
1 (6 1/2 oz.) can water packed tuna, drained
3 tbsp. minced onion
2 tbsp. minced celery
2 tbsp. water chestnuts, finely chopped
1/3 c. safflower mayonnaise
Dash prepared mustard (optional)

Sprinkle lemon juice over tuna; toss with onion, celery, and water chestnuts. Moisten with mayonnaise; mix with mustard.