1. Generously season the ribs on all sides with salt and pepper.
2. In a six-quart slow cooker, whisk together barbecue sauce, beef stock, mustard, and mustard seeds.
3. Heat the oil in a heavy pot over medium-high heat. Brown the ribs on all sides, three to four minutes. Transfer the ribs to the slow cooker. Pour out any fat in the pot.
4. Return the pot to the heat, add the wine, and bring to a boil, scraping up any bits from the bottom. Then transfer to the slow cooker with the ribs. Cover and cook until the ribs are tender, five to six hours on high, or eight to nine hours on low. Transfer the ribs to a platter and pour enough of the sauce over the ribs to coat.