In a large bowl, combine the first five ingredients. Add the beans, onion and mushrooms; toss to coat. , Place half of the vegetables on a double thickness of heavy-duty foil (about 18 in. square); fold foil around vegetables and seal tightly. Repeat with remaining vegetables., Grill, covered, over medium heat for 18-22 minutes or until beans are tender, turning packets over once. Open foil carefully to allow steam to escape. ,