Remove the zampone from its bath and rinse in cold water. Pat dry.
In a large bowl, thoroughly combine the pork meat, ham skin, the prosciutto, the Italian sausage and the spices. Season the inside of the zampone with salt and pepper and stuff with the pork mixture. Using a large needle and butcher's twine, truss the leg. In a large pot, place the zampone with enough water to cover by several inches. Place over high heat and bring to a boil. Lower the heat and simmer covered for 2 hours.
Meanwhile peel and quarter potatoes and place in a large pot and cover with cold water. Bring the potatoes to a boil over high heat and cook until tender, approximately 10 minutes. Once potatoes are cooked drain them and mash using potato masher, ricer or food mill. Add the butter and enough of the milk to make a loose yet homogenized mixture. Season with salt and pepper to taste. Reserve warm until ready to serve.
When the zampone is done, remove from the water, allow to rest 10 minutes, then slice into 1/2-inch rounds and place on top of the warm potatoes. Drizzle with real balsamic vinegar and serve.
Recipe copyright 2000, Mario Batali. All Rights Reserved.