1. In large bowl, combine all ingredients except butter; stir in butter. Evenly divide mixture onto two 12 x 18-inch pieces heavy-duty aluminum foil. Wrap foil loosely around potato mixture, sealing edges airtight with double fold.
2. Grill, seam side down, turning once, 20 minutes or until potatoes are tender.
Tip: To bake in the oven, on jelly-roll pan, arrange packets, seam side down. Bake at 450°, turning once, 40 minutes or until potatoes are tender.