Preheat the oven to 275° F. Line a baking sheet pan with foil
Rinse the rack of ribs, pat dry, and pull the thin membrane off the back of the ribs. This is optional, but highly recommended, and easy to do. It makes the ribs easier to eat and allows the rub to sink in. It usually pulls off in one big sheet.
Blend the rub seasoning mix in a small bowl, if using.
Lay rack of ribs on the foil-lined baking pan, brush with olive oil and generously smear the rib rub all over the ribs (bottom, sides, and top). If you want the ribs less spicy you can skip the rub and just season with ground pepper and salt.
Tightly cover the baking sheet with foil. The ribs should be meat-side up.
Bake the ribs for about 3-3.5 hours for St. Louis style ribs, and about 2.5 hours for baby back ribs. Uncover and check for tenderness. The ribs should be pulling away from the bone at this point and fork-tender.
Remove ribs from the oven, and increase cooking temperature to 350° F. If any liquid has accumulated in the pan drain it off. Coat the ribs generously with the BBQ sauce, if using. Return to oven, uncovered, and let the ribs bake for an additional 20 minutes. If you prefer your BBQ sauce more caramelized then finish by broiling the ribs for about 2 minutes on low broil. Remove from the oven and let the ribs rest for 10-minutes before cutting and serving.