Heat grill. Beat egg in medium bowl. Add bread crumbs, onion, hot pepper sauce and tuna; mix well. Shape mixture into 4 patties, 3/4 inch thick.
When ready to grill, place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 8 to 10 minutes or until deep golden brown, turning once.
Place lettuce on bottom halves of buns. Top each with patty, tomato and top half of bun. Serve with tartar sauce.