Heat the oil in a large, heavy skillet over medium-high heat. Pat the meat dry and add only as many pieces to the pan as will fit comfortably without crowding. Cook until nicely browned on all sides. Transfer the meat to a large slow cooker and brown the remaining meat. Sprinkle the ribs with salt and pepper to taste. Discard all but 1 tablespoon of the fat and reduce the heat to medium.

Add the garlic and cook for 1 minute. Add the wine and vinegar and bring to a simmer, scraping the bottom of the pan. Pour the liquid over the ribs and add the rosemary.

Cover and cook on low for 8 hours, or until the ribs are very tender. Remove the ribs from the slow cooker and discard the rosemary sprig and any loose bones. Cover the ribs and keep warm.

Skim the fat off the liquid. Pour the remaining sauce into a saucepan and cook over medium-high heat until reduced and slightly thickened. Spoon the sauce over the ribs and serve hot.