Preheat the oven to 325 degrees F (165 degrees C).

Heat oil over medium heat in a large, heavy, oven-safe pot or Dutch oven. Add ribs; brown on all sides, about 5 minutes, working in batches if necessary. Season ribs with black pepper as they brown. Transfer browned ribs to a paper-towel-lined plate to drain.

Stir onion rings and carrots into same pot; cook and stir until onions turn translucent and start to brown, about 8 minutes. Stir in garlic; cook until fragrant, about 1 minute more. Stir in tomato sauce, barbecue sauce, and beef broth; bring to a boil, and simmer for 1 minute to blend flavors. Stir in browned ribs.

Cover pot; bake in the preheated oven until the meat is very tender, turning ribs occasionally, about 2 1/2 hours. Season to taste before serving.