Preheat the oven to 300°F.

Put the baby back rib racks on a large sheet of heavy-duty aluminum foil, meat side up. In a mixing bowl, stir together the ½ cup of barbecue sauce and the orange juice and spread the mixture over the rib racks. Tightly seal the ribs and sauce inside the foil, place the package on a rimmed cookie sheet, and place on the middle oven rack. Bake for 3 hours.

Preheat an outdoor grill to a high temperature.

When the baking time is over, remove the foil package from the oven and, over the sink, carefully drain off the liquid that has accumulated inside, keeping your hands safely clear. With heavy-duty grilling tongs, carefully remove the rib racks from the package, keeping them whole.

With the tongs, place the rib racks on the grill meat side up. Baste the top side of ribs with your favorite barbecue sauce. Cover and grill for 3 to 4 minutes. Then, uncover the ribs, turn over the racks, cover again, and grill for another 3 minutes. Check to see if the meat side of ribs has browned enough and either remove the ribs from the grill or grill for another minute or so until perfectly browned.

Transfer the rib racks to a cutting board. Depending on the size of the ribs, use a large, sharp knife to cut the racks between the bones into 4-to-6-rib portions.  Serve additional barbecue sauce at the table.