Preheat the oven to 350°F. Remove the membrane from the back of the ribs and pat dry. Lightly coat both sides with yellow mustard.
In a small bowl, combine the salt, brown sugar, smoked paprika, garlic powder, onion powder, black pepper, cumin, and chili powder. Season the ribs generously on both sides.
Place the ribs on a large rimmed baking sheet and cover tightly with foil. Bake for 2 to 2½ hours, until the ribs are extremely tender.
BBQ sauce- combine all sauce ingredients in a saucepan and bring to a simmer over medium heat. Cook for 10–15 minutes, stirring occasionally, until thickened and glossy.
Remove the ribs from the oven and brush generously with BBQ sauce.
Increase the oven temperature to 425°F or switch to broil. Return the ribs to the oven and cook for 5–8 minutes, or until the sauce is bubbling and caramelized. WATCH CLOSELY- sauce can burn quickly.
Let rest for 5–10 minutes, then slice between the bones and serve with extra BBQ sauce.
