Preheat oven to 300°F (150°C) with a rack in the center position.
Combine salt, chili powder, paprika, garlic powder, onion powder, pepper, and cayenne for the spice rub.
Remove the thin clear membrane from the back of the ribs using a paring knife and paper towel.
Rub the spice seasoning all over the ribs, ensuring full coverage.
Place seasoned ribs, meat-side up, on a large rimmed sheet pan and cover tightly with foil.
Bake for 2.5 to 3 hours until very tender (190-200°F internal temperature).
Remove foil, drain liquid, and brush ribs generously with BBQ sauce. Increase oven to 375°F (190°C).
Bake for another 15-20 minutes until the sauce is caramelized and sticky. Serve immediately.