In cup, combine soy sauce, ginger, sugar, crushed red pepper, and garlic; set aside. Heat nonstick 10-inch skillet over medium-high heat until hot. Add chicken and cook 4 to 5 minutes or until no longer pink, breaking up meat with side of spoon.
Add celery to chicken in skillet, and cook 2 minutes, stirring occasionally. Add water chestnuts and soy-sauce mixture; cook 1 minute to blend flavors. Stir in peanuts. Divide chicken mixture among lettuce leaves. Fold leaves over chicken mixture and eat out of hand.