In a small bowl, combine the rosemary
, onion, and pork fat, mixing thoroughly with your hands or the back of a spoon to form a paste. Work quickly to avoid raising the temperature of the fat and melting it.
In a heavy-bottomed skillet, heat the herb, onion and fat mixture until the onion is translucent and the rosemary is fragrant. Season the mutton cubes with salt and pepper and brown on all sides in the fat, then add the wine and cook over high heat for 2 minutes.
Add the tomatoes, season with salt and pepper, to taste, and simmer, covered, for about 90 minutes, until the flavors have melded and the meat is falling apart.
Meanwhile, make the pasta according to the recipe and roll it out to the thinnest setting on a pasta-rolling machine. Using a paring knife, cut the pasta into uneven shapes and allow to dry.
Bring 6 quarts of water to a boil and add 2 tablespoons salt. Add the pasta and cook 6 minutes, until tender yet al dente. Drain the pasta and add it to the pan with the lamb ragu.
Toss over high heat 1 minute, then divide evenly among 4 warmed pasta bowls. Top with grated pecorino and serve immediately.