Drain pineapple, reserving 3 tablespoons juice. In a small bowl, combine the soy sauce, vinegar, cornstarch, garlic, ginger, pepper and reserved pineapple juice; set aside.
In a large skillet, cook sausage over medium heat until no longer pink; drain. Stir in water chestnuts and crushed pineapple. Gradually stir in soy sauce mixture. Bring to a boil; cook and stir for 2 minutes or until thickened.
Place about 2 tablespoons sausage mixture on each lettuce leaf; fold lettuce over filling. Top with a pineapple chunk; secure with a toothpick. Sprinkle with sesame seeds and serve with teriyaki sauce if desired. Yield: 2-1/2 dozen.