Brodo: 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.
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 1/2 cups of the flour in the center of a large wooden cutting board. Make a well in the middle of the flour and add the eggs and the olive oil. Using a fork, beat together the eggs and oil and begin to incorporate the flour, starting with the inner rim of the well.
As you expand the well, keep pushing the flour up from the base of the mound to retain the well shape. The dough will come together when half of the flour is incorporated.
Start kneading the dough with both hands, using the palms of your hands. Once you have a cohesive mass, remove the dough from the board and scrape up and discard any leftover bits. Lightly reflour the board and continue kneading for 6 more minutes. The dough should be elastic and a little sticky. Wrap the dough in plastic and allow to rest for 30 minutes at room temperature. Roll or shape as desired.
To assemble the dish: Cut the prepared pasta dough into 3 equal portions. Using a pasta machine, roll out the pasta to the thinnest setting then cut the sheets into 2-inch squares. Place 1 teaspoon of the tortellini filling in the center of each 2-inch square. Fold the opposite corners together to form a triangle and press the edges together firmly to seal. Bring the long points of the triangle together and join with firm finger pressure. Continue filling and shaping tortellini until all the pasta and filling are used. Set the tortellini on a sheet tray, covered with a clean, damp towel.
Bring the prepared brodo to a boil and season with salt and pepper. Drop the tortellini into the brodo and cook until tender, about 3 to 4 minutes. Remove tortellini from the brodo with a slotted spoon, and divide among 10 to 12 heated pasta bowls. Spoon some of the brodo into each bowl and serve immediately, topped with freshly grated Parmigiano-Reggiano.