1 head Savoy cabbage (about 2 1/2 pounds), cored
2/3 cup raw medium-grain rice
1 1/2 pounds mild Italian sausage or garlic sausage, casing removed and meat crumbled
2 large garlic cloves, peeled and finely chopped
3 tablespoons unsalted butter
1 medium onion, peeled and finely chopped
6 ounces pork tenderloin, cut into small dice
3 ripe plum tomatoes, peeled, seeded, and chopped
1/2 cup frozen or fresh peas
Salt and freshly ground black pepper to taste
1 quart beef broth
1/2 pound boneless lamb or mutton neck or shoulder meat, trimmed of fat, cut into small pieces
1. Remove and discard any of the outermost leaves of the cabbage that are blemished. Bring a large pot of water to a rolling boil and plunge the whole cabbage in until the leaves can be unrolled without ripping, about 10 minutes. Drain well and, when cool enough to handle, separate the leaves carefully, setting them aside to be rolled later. Finely chop the innermost section of the cabbage, about 1/2 pound of cabbage. Set aside.
2. Place the rice in a small strainer and dip the rice-filled strainer into a pot of lightly salted boiling water for 1 minute. Blanching or rinsing the rice removes the starch that would otherwise make it sticky. Remove and set aside. Toss the sausage meat with the garlic.
3. In a large skillet melt 2 tablespoons butter over medium-high heat, then cook the onion until translucent, about 5 minutes, stirring occasionally. Add the remaining tablespoon butter; once it has melted, add the diced pork tenderloin and brown, 3 to 4 minutes, stirring. Set aside.
4. Lay the cabbage leaves in front of you on a work surface and layer the pork and onion, the chopped tomatoes, rice, peas, and sausage meat on one side, in that order, on top of one another. Season with salt and pepper. Roll the cabbage leaves up, tucking in the sides. It will be a package the shape of a ball. Repeat with the remaining leaves and filling. You should have about 12 stuffed cabbage leaves.
5. Arrange the stuffed cabbage in a casserole that will hold all of them tightly in one or two layers. Cover with the beef broth and lamb or mutton neck meat. Cover and bring to a gentle boil over medium-high heat. As soon as the water starts to bubble, reduce the heat to low, and simmer until the rice inside the cabbage is tender, about 3 1/2 hours.