Season the beef with salt and pepper. Heat the oil in a heavy large pot over medium-high heat. Add beef and brown on all sides, about 12 minutes. Transfer beef to platter; reduce heat to medium.
Add onion and pancetta to pot. Sauté until onion is golden, about 8 minutes. Mix in tomato paste, bay leaves, cloves and rosemary. Add wine. Return meat and any juices to pot. Cover and simmer 30 minutes, turning meat once.
Mix stock and tomatoes into sauce. Cover and simmer gently until meat is tender, turning occasionally, about 3 hours.
Transfer beef to platter. Cover with foil to keep warm. Strain sauce through fine sieve, pressing on solids to extract as much liquid as possible. Discard solids. Degrease sauce. Return sauce to pot and boil until reduced to 2 cups, about 1 hour. Add any beef juices from platter to sauce. Cut beef across grain into ⅓-inch thick slices. Return sliced meat to sauce. Rewarm gently. Arrange meat on platter, spoon sauce over and serve.