Flip the rack bone-side up and locate the thin silvery membrane on the back. Slide a butter knife under the membrane at one end, grip with a paper towel, and peel it off in one pull. Discard the membrane.

In a small bowl, combine smoked paprika, garlic powder, onion powder, cumin, brown sugar, salt, black pepper, and cayenne (if using). Mix well.

Pat the ribs dry with paper towels on both sides. Generously coat all surfaces of the rack with the dry rub, pressing it firmly into the meat. For best results, let the rubbed ribs rest for at least 30 minutes at room temperature, or up to 24 hours covered in the refrigerator.

Pour the chicken broth and apple cider vinegar into the bottom of the Instant Pot insert.

Place the trivet (rack) inside the pot. Cut the rib rack in half or thirds if needed to fit. Stand the rib sections upright in a circular arrangement around the trivet, bone-side facing out.

Secure the lid and set the valve to Sealing. Cook on Manual / Pressure Cook (High Pressure) for 25 minutes.

Once the cook time is complete, allow a full natural pressure release for 15 minutes, then carefully switch the valve to Venting to release any remaining steam. Remove the lid.

Preheat your oven broiler to High. Line a rimmed baking sheet with foil and lightly grease.

Carefully transfer the cooked ribs to the prepared baking sheet, bone-side down. Brush a generous layer of BBQ sauce over the top and sides of the ribs.

Place under the broiler 6–8 inches from the heat source. Broil for 3–5 minutes, watching closely, until the sauce is bubbling, caramelized, and slightly charred at the edges.

Remove from the oven and let rest for 5 minutes. Brush with additional BBQ sauce if desired, then slice between the bones and serve immediately.