Heat the oil in a large non-reactive pot or Dutch oven over medium heat. Add the lamb and season with salt and crushed red pepper. Cook, stirring, until the lamb is browned and all pink has disappeared, 4 to 6 minutes. Add the onions, celery, and carrots and cook, stirring, until they are soft, 3 to 5 minutes. Add the garlic and tomatoes, and season with salt and black pepper. Cook, stirring, for 2 to 3 minutes. Whisk the tomato paste with the stock or water and add to the pot. Add the thyme, bay leaves, oregano, basil and season with crushed red pepper. Mix well and bring the mixture to a boil. Reduce the heat to medium-low and simmer, stirring occasionally, for 1 1/2 hours. If the mixture becomes dry, add a little stock or water. Correct seasoning if necessary. Add the cheese and cook for 30 minutes. Remove from the heat and let sit for 15 minutes before using.
Makes about 5 cups