How to Make It
Preheat the oven to 375°. In a large enameled cast-iron casserole, heat the oil. Season the ribs with salt and pepper. Add the ribs in batches and brown them on all sides over moderately high heat. Remove the ribs to a plate and pour off all but 2 tablespoons of fat from the casserole. Add the carrots, celery and onion and cook, stirring often, until browned, about 10 minutes. Stir in the tomato paste and cook for 4 minutes longer. Pour in the vinegar and boil over high heat, scraping up any browned bits. Stir in the stock, tomatoes, brown sugar and molasses, add the ribs and bring to a boil.
Cover and braise the ribs in the oven for about 2 hours, turning them occasionally, until the meat is very tender. Remove the ribs to a large platter and cover with foil to keep warm. Skim off all the fat from the cooking liquid. Pour the contents of the casserole through a fine strainer, pressing hard on the vegetables. Bring the sauce to a boil and season with salt and pepper. Pour the sauce over the ribs and serve.