Trim fat from steak; cut steak into 1-inch pieces. Place steak in a heavy-duty, zip-top plastic bag. Combine wine and next 6 ingredients in a small bowl, stirring well. Pour wine mixture over steak. Seal bag, and shake until steak is well coated. Marinate in refrigerator at least 8 hours, turning bag occasionally.
Remove steak from marinade, reserving marinade. Thread steak, onion, sweet red pepper, zucchini, yellow squash, and mushrooms alternately onto 4 (10-inch) skewers.
Coat grill rack with cooking spray; place on grill over medium-hot coals (350° to 400°). Place kabobs on rack; grill, covered, 12 to 14 minutes or to desired degree of doneness, turning and basting frequently with reserved marinade.