For each papillote, place three carrots of different colours
in the centre of a sheet of heavy-duty aluminum foil. Drizzle with a quarter of the oil and vinegar mixture. Add an ice cube. Season with salt and pepper. Fold in the sides of the foil and tightly seal the papillote. Place on the grill, close the lid, and cook for about 25 minutes, depending on the size of the carrots, or until al dente.
