Combine taco seasoning, brown sugar, tomato sauce, and pureed chillies in a large mixing bowl. Add ribs and coat with sauce. Cover and refrigerate to marinate for at least 2 hours. Reserve marinade.
Preheat the oven to 325º F.
Heat oil in a cast iron skillet over medium heat. Sear ribs for 5 – 8 minutes, or until brown on all sides.
Add halved garlic heat, cut side down, and reserved marinade, Pour wine, scraping up the bits at the bottom. Bring to a boil and cook for 3-5 minutes to reduce. Add beef stock, basting the ribs with the juices.
Cover skillet with foil and cook in the preheated oven for 2 - 3 hours, basting occasionally, or until the meat is tender and falling away from the bone. Uncover and cook for 15 – 30 minutes, basting the juices one more time.
When ready to serve transfer the ribs to a serving dish. Spoon off any excess fat from the cooking juices and then strain it through the sieve. Squeeze garlic out of their skins and pass through a sieve. Mix cooking juices and garlic and pour sauce over the ribs.
Garnish with cilantro and serve with lime- cilantro rice, if desired.