Chop the guanciale into 1-inch batonettes and place in a cold pan over medium heat. Cook until the fat is rendered, about 5 to 6 minutes, and add the radicchio. Saute over medium heat until the leaves are wilted, then add the rosemary, vinegar and salt and pepper, to taste, and toss to coat. Serve hot or at room temperature.
Recipe copyright 2000, Mario Batali. All Rights Reserved.