A good pork roast is as sublime as it is uncommon: Its flesh is tender and juicy, its skin delicate and crisp. But how do you get that superb crackly exterior without overcooking the meat? One solution is to cook the skin and meat separately. Vacuum seal the pork in plastic and slow-cook in a water bath until the meat reaches the same temperature throughout. Meanwhile, gelatinize and fry the detached skin and sprinkle it on the loin. Here we garnish it with edible "coals" made out of stewed prunes and caramel foam.