Cook chicken in skillet,remove from pan to cutting board. Add onion to skillet. Finely chop chicken. Return to skillet. For ground beef - while meat is cooking, chop onion and add to skillet. Turn skillet to med/high and add in soy sauce, garlic, hoisin sauce, ginger, rice vinegar, and chili pepper sauce. Cook for 5-10 minutes. Add in water chestnuts, green onion, and sesame oil, stir fry for another 2 minutes. Put in serving dish. Rinse lettuce and pat dry. Spoon chicken/beef mixture into wraps, fold and enjoy.