Season lamb pieces with salt and pepper. In a heavy-bottomed Dutch oven, heat olive oil over medium heat. Add lamb pieces 5 to 6 at a time and brown on all sides. Remove and repeat for all lamb. When lamb is cooked, add onions and smoked pancetta and cook until onion is softened and starting to brown, about 9 to 11 minutes. Add rosemary, thyme, caraway and fennel and stir to blend. Add wine, tomato paste, chicken stock and tomato sauce and bring to a boil. Add lamb and juices on plate and return to boil. Lower heat, cover and simmer 1 hour, or until meat is tender. Remove cover, check seasoning and serve with soft polenta.
Saute the onion and garlic in the olive oil over medium heat until translucent, but not brown (about 10 minutes). Add the thyme and carrot and cook 5 minutes more. Add the tomatoes. Bring to a boil, lower the heat to just bubbling, stirring occasionally for 30 minutes. Season with salt to taste. Serve immediately, or set aside for further use. The sauce may be refrigerated for up to one week or frozen for up to 6 months.
In a 4quart saucepan, place cool water over high heat and bring water to a boil. Season with salt and pepper. Add polenta in a thin stream, whisking constantly. When all polenta is in, pull pot to front of burner, remove whisk, and start stirring with a wooden spoon.