How to Make It
In a medium enameled cast-iron casserole, heat 1/4 cup of the olive oil until shimmering. Add the carrots, onion and red bell pepper and cook over moderate heat, stirring occasionally, until softened and just beginning to brown, about 12 minutes. Using a slotted spoon, transfer the vegetables to a plate.
Heat the remaining 2 tablespoons of oil in the casserole. Add the pancetta and stir once or twice over moderately high heat until sizzling. Add the lamb and cook, stirring occasionally, until the liquid has evaporated and the meat is browned, 10 minutes. Return the vegetables to the casserole. Add the red wine and simmer until evaporated, scraping up any browned bits from the bottom of the casserole. Add the tomatoes and their juices, the chicken stock, bay leaf and crushed red pepper. Season with salt and black pepper and bring to a boil. Reduce the heat to moderately low, cover partially and simmer, stirring occasionally, until the lamb is very tender, 1 1/2 hours. Discard the bay leaf.
In a large pot of boiling salted water, cook the rigatoni until al dente. Drain the rigatoni and toss with half of the lamb ragù. Serve the pasta in large bowls, passing the remaining lamb ragù and the Pecorino cheese at the table.