Heat grill. If potatoes are large, cut in half. Place potatoes in disposable foil pan or in center of large sheet of heavy-duty foil. In small bowl, combine butter, garlic and salt; pour over potatoes. Seal pan with foil or seal foil packet. When ready to barbecue, place potatoes on gas grill over medium heat or on charcoal grill 4 to 6 inches from heat of medium-high coals. Cook 50 to 60 minutes or until potatoes are tender.
Oven method: Heat oven to 400 degrees. Prepare potatoes as directed above. Bake at 400 degrees for 50 to 60 minutes or until potatoes are tender.