Preheat the oven to 275ºF. Use a sharp knife to slide under the thin membrane on the underside of the ribs and peel it off. Cut the rack into sections that will fit comfortably in your Dutch oven.
In a small bowl, combine the brown sugar, smoked paprika, onion powder, oregano, garlic powder, mustard powder, coriander, salt, and black pepper. Rub half of the spice mixture all over the ribs.
Add the barbecue sauce and beef stock to the bowl with the remaining spice rub. Stir well to create the cooking sauce.
Arrange the ribs in the Dutch oven, then pour the sauce mixture over the top. If using, tuck the half orange into the pot. Cover with the lid.
Bake for 2 1/2 to 3 hours, or until the ribs are tender and the meat is beginning to pull away from the bones. They should reach a minimum internal temperature of 145°F for safety, but the 190°–203°F range is ideal for tenderness.
Remove the ribs from the oven. Squeeze the orange over the ribs, if desired, then discard the orange.
Let the ribs rest for 10-15 minutes. Brush or spoon some of the sauce from the pot over the ribs, if desired, and serve warm.