When purchasing potatoes for this recipe, look for ones about the size of an extra-large egg and that weigh about 2 ounces each. And for even cooking, try to select potatoes of similar shape and size. The potatoes can be precooked and refrigerated up to a day in advance; just before grilling, skewer them, brush with lard and season with salt and pepper. You'll need three or four sturdy 12- to 14-inch metal skewers; skewers with pins that are flat rather than round or square help prevent the potatoes from spinning around, making them easier to manage on the grill. If you're preparing this recipe to serve with Armenian-style grilled pork chops, place the skewered potatoes on the hot side of the grill after you've removed the chops and allow the potatoes to brown while the chops rest.