01 -
Pat the ribs dry with paper towels. Season them with 1/2 teaspoon salt and the black pepper.
02 -
Heat the oil in a large skillet over medium-high heat. Sear the ribs in batches for about 2 minutes per side, just until browned, then transfer them to a 6-quart slow cooker.
03 -
In a bowl, whisk the ketchup, tomato paste, brown sugar, vinegar, broth, mustard, Worcestershire sauce, smoked paprika, garlic powder, onion powder, cayenne if using, and remaining 1/2 teaspoon salt until smooth.
04 -
Pour the sauce over the ribs and turn them to coat. Cover and cook on Low for 8 hours, or on High for 4-5 hours, until the meat is very tender.
05 -
Carefully transfer the ribs to a foil-lined baking sheet. Spoon excess fat from the sauce. For a thicker glaze, simmer the sauce in a saucepan for 8-12 minutes.
06 -
Brush the ribs generously with sauce. Broil 4-6 inches from the heat for 3-5 minutes until bubbling and lightly charred at the edges. Serve with extra sauce.