Bring the brodo to a boil. Add the tortellini and cook for 8 to 10 minutes, until all the tortellini are floating to the top of the pot. Ladle equal portions of tortellini into 4 warmed pasta bowls. Ladle the hot broth on top of the tortellini, top with grated Parmigiano.
Place the beef, bones, tongue, chicken pieces, onion, carrot, and celery in a large soup pot, cover with the water and bring almost to a boil, very slowly. Reduce the heat to simmer before the mixture boils, and allow to cook for 4 hours, skimming off the foam and any excess fat that rises to the surface. After 4 hours, remove from heat, strain the liquid twice, first through a conical sieve and second through cheesecloth, and allow to cool. Refrigerate stock in small containers for up to a week or freeze for up to a month.
Filling: In a Dutch oven or heavy-bottomed, large saucepan, heat the butter and oil until it foams and subsides. Add the turkey, veal and pork shoulder and cook over high heat, stirring occasionally, until the meat is well-browned and begins to release some of its juices. Add the prosciutto and mortadella and cook for 5 minutes more. Remove from heat and allow to cool. Place in a food processor and mix to combine. Add the egg and the Parmigiano-Reggiano and mix well to combine. Season with salt and pepper, to taste, and add at least 1/4 teaspoon freshly grated nutmeg and mix again. Set aside in the refrigerator until ready to use.
Pasta: Mound 3 cups of flour in the center of a large wooden cutting board. Make a well in the middle of the flour, add the eggs and oil. Using a fork, beat together the eggs and begin to incorporate the flour starting with the inner rim of the well. As you incorporate the eggs, keep pushing the flour up to retain the well shape (do not worry if it looks messy). The dough will come together in a shaggy mass when about half of the flour is incorporated.
Start kneading the dough with both hands, primarily using the palms of your hands. Add more flour, in 1/2-cup increments, if the dough is too sticky. Once the dough is a cohesive mass, remove the dough from the board and scrape up any left over dry bits. Lightly flour the board and continue kneading for 3 more minutes. The dough should be elastic and a little sticky. Continue to knead for another 3 minutes, remembering to dust your board with flour when necessary. Wrap the dough in plastic wrap and set aside for 20 minutes at room temperature.
Roll the pasta into sheets using a pasta machine. For the desired pasta sheet thickness, gradually pass the dough through the settings starting with the widest and continuing to the number 9 setting.
With a pasta cutter or a knife, cut the pasta into 1 1/2-inch squares. Place 3/4 teaspoon of filling in the center of each square. Fold into triangles, press out any air around the filling, and press to seal the edges. Bring the points of the long side together to form a ring, and seal between your fingers.
Set the tortellini aside on a sheet pan, wrap well with plastic wrap, and refrigerate. Reserve for later assembly.
Yield: 1 1/4 pounds
Recipe copyright 2001, Mario Batali. All Rights Reserved.