- Preheat the grill, setting the burners on high.
- For each papillote, spread butter in the centre of each aluminum foil square. Place the potatoes, cut side down, on the butter. Sprinkle with the onions. Season with salt and pepper. Close and seal.
- Reduce the grill’s temperature to medium-low. Bake with the lid closed for about 35 minutes or until the potatoes are tender.