Peel or leave the skins on medium size baking potatoes. Slice them into about one-quarter inch thick slices, without going all the way through. Put a thin slice of onion and a small piece of cheese between the potato slices, give a brushing with some melted butter and sprinkle with salt and pepper. Wrap tightly in foil and place on the grill about an hour and a half before serving time. When the potato feels soft through the foil, it’s done.