To cook some food on the grill to a moist, succulent finish, many recipes call for foil packets. In a technique called drugstore wrap, heavy-duty foil encloses food with tight double folds.
To make a foil packet, place food in the centre of a piece of foil large enough to enclose the food one and a half times. Bring the shortest edges together over the food and fold them over about 2.5 cm (1 inch). Continue to fold until it lies flat and snug against the food. To seal ends, fold them into triangles and tuck under the packet.