Heat 1 tablespoon oil in small skillet. Add onion, celery and green pepper. Cook and stir over moderate heat until tender. Place in medium mixing bowl. Add salmon, egg, bread crumbs, mayonnaise, chili sauce, lemon juice, salt and pepper. Mix well.
Place potato flakes in shallow dish or on sheet of waxed paper. Place scant 1/2-cup salmon mixture on potato flakes. Flatten to form a patty 3/4-inch thick. Coat both sides with potato flakes. Repeat with remaining salmon mixture to form 4 patties.
Heat remaining 4 tablespoons oil in large skillet. Add patties. Fry over moderate heat 6 to 8 minutes, or until golden brown and firm, turning over once. Drain on paper towels.
Serve on buns with lettuce and tartar sauce, if desired.
Follow recipe above, substituting 1 (6 1/2 oz.) can tuna, drained and flaked, for salmon.
Follow recipe above, substituting 1 (6 oz.) can crab meat, drained, cleaned and flaked, for salmon.