Combine first 3 ingredients. Add turkey; cover and marinate in refrigerator 30 minutes. Remove turkey from marinade; reserve marinade. Place marinade in a saucepan; bring to a boil. Remove from heat.
Thread turkey and onion alternately onto 4 (8-inch) skewers. Broil 5 1/2 inches from heat (with electric oven door partially opened) 3 minutes on each side or until turkey is done, basting with marinade.