01 - Peel the silver skin membrane from the underside of each rack of ribs using a sharp knife and a paper towel for grip, ensuring better tenderness and spice absorption.
02 - Combine the brown sugar, smoked paprika, garlic powder, onion powder, black pepper, salt, chili powder, and cayenne pepper in a small bowl, mixing until evenly blended.
03 - Coat both sides of each rack thoroughly with the spice rub mixture, pressing it into the meat. Allow the ribs to rest at room temperature for at least 30 minutes, or wrap and refrigerate overnight for deeper flavor penetration.
04 - Set your grill to medium heat (275–300°F) and configure it for indirect grilling by banking coals to one side or turning off burners on one half of a gas grill.
05 - Wrap each rack tightly in aluminum foil and place bone-side down over the indirect heat zone. Close the grill lid and cook for 1 hour and 30 minutes until the meat is tender and pulling away from the bones.
06 - Carefully unwrap the ribs from the foil and brush generously with barbecue sauce. Place the ribs directly over medium heat and grill for 10–15 minutes, turning and basting with additional sauce every few minutes until the exterior is caramelized and lightly charred.
07 - Transfer the ribs to a cutting board and let rest for 5 minutes to allow the juices to redistribute. Slice between the bones into individual ribs and serve immediately.