How to Make It
Wash the ribs and blot dry. Remove the thin papery skin on the back of each rack of ribs. (Pull it off in a sheet with your fingers, using a corner of a dish towel to gain a secure grip.)
Combine the ingredients for the rub in mixing bowl and stir with your fingers to mix. Rub 2/3 of this mixture on the ribs on both sides. Transfer the ribs to a roasting pan and let marinate for at least 4 hours, preferably overnight.
In a small bowl, whisk together the ingredients for the mop sauce.
Place the ribs on the grill over the drip pan and cover the grill. Start basting with mop sauce after 30 minutes, basting every 20 minutes. Cook the ribs for 1 1/4 to 1 1/2 hours until done. The ribs are done when the meat is very tender and it has shrunk back from the ends of the bones. If using a charcoal grill, replenish the coals after 1 hour.
Transfer the ribs to a cutting board or platter. Mop one final time with mop sauce and sprinkle with the remaining rub. Serve with your favorite barbecue sauce on the side.