Remove the membrane: Flip the ribs bone-side up. Slide a butter knife under the silverskin membrane at one end, grip it firmly with a paper towel, and peel it off in one continuous strip. Discard the membrane.

Make the dry rub: In a small bowl, combine smoked paprika, brown sugar, garlic powder, onion powder, cumin, kosher salt, black pepper, cayenne, and mustard powder. Stir until well mixed.

Season the ribs: Cut each rack into 3-4 rib sections to fit your Instant Pot. Generously coat all sides of the ribs with the dry rub, pressing it firmly into the meat. For best flavor, let the ribs rest for at least 15-30 minutes at room temperature, or refrigerate uncovered for up to 24 hours.

Add liquid to the Instant Pot: Pour the chicken broth and apple cider vinegar into the bottom of the Instant Pot insert. Place the trivet inside.

Load the ribs: Stand the rib sections upright on the trivet, leaning them against the sides of the pot with the meaty side facing out. It's okay if they overlap slightly.

Pressure cook: Secure the lid and set the valve to Sealing. Cook on Manual / Pressure Cook on HIGH for 25 minutes. When the cycle completes, allow a natural pressure release for 15 minutes, then carefully switch the valve to Venting to release any remaining pressure.

Preheat the broiler: While the pressure releases, preheat your oven broiler to HIGH. Line a rimmed baking sheet with foil and lightly grease it.

Broil the ribs: Carefully transfer the cooked rib sections to the prepared baking sheet, bone-side down. Brush generously with barbecue sauce. Broil on the top rack for 5-7 minutes, watching closely, until the sauce is caramelized, bubbling, and lightly charred in spots.

Add second coat and rest: Remove from the broiler and brush on a second layer of barbecue sauce. Let the ribs rest for 5 minutes before slicing and serving. Serve with extra BBQ sauce on the side.