Heat peanut oil in a large skillet over medium-high heat. Add onions, cornstarch, and chicken to pan; sauté for 4 minutes or until chicken is done, stirring to crumble. Add persimmon, water chestnuts, ginger, soy sauce, juice, and oyster sauce to pan; cook for 2 minutes. Remove from heat. Spoon 1/4 cup chicken mixture into center of each lettuce leaf; roll up jelly-roll fashion.