Preheat the oven to 250°F.

Position a roasting rack inside a large roasting pan. Pour the chicken broth into the pan. Set aside.

Season the pork ribs liberally with salt and black pepper on both sides.

In a small bowl, whisk together the brown sugar, paprika, ground mustard, garlic powder, onion powder, cumin, and cayenne pepper.

Using a spoon and clean hands, pat the sugar and spice rub evenly onto both sides of the pork ribs.

Place the ribs meat side up on the roasting rack. Cover the pan entirely with a large sheet of aluminum foil. Crimp the foil tightly around the edges of the pan so that no steam can escape.

Roast the ribs on middle rack of oven until they reach an internal temperature of about 180°F and are very tender, 2 1/2-3 hours.

Remove the roasting pan from the oven.

Very carefully remove the foil from the pan. Spread the barbecue sauce evenly over the top of the ribs.

Set the oven to broil. Broil the ribs on the top rack of oven until the barbecue sauce starts to caramelize, 4-5 minutes. Keep a close eye on the ribs to ensure they do not burn.

Check to see that ribs are done. Remove from oven or add time as needed.

Allow the ribs to cool for 3-4 minutes on the roasting rack, then transfer to a cutting board. With a sharp knife, cut the ribs into desired portions, and serve immediately. Garnish with fresh rosemary if you like.