Mix together soy sauce, lime juice, Worcestershire sauce, garlic and mustard. Place chicken in a bowl and pour sauce over all. Cover and marinate in refrigerator for 30 minutes. Remove chicken from marinade. Sprinkle with black pepper. Spray non-stick fry pan with butter flavored cooking spray. Heat over medium temperature. Add chicken and cook about 6 minutes on each side or until fork can be inserted in chicken with ease.
