Prepare fire in the charcoal grill. Remove the grates, place a pile of charcoal on one side of the grill only. On the other side, place a small foil pan filled with water. Start the fire and return the grates to the grill. Let the grill get to a low temperature (about 275°F.) You may also add pieces of wood to the charcoal for a more smoky flavor.
While the fire is heating, prepare ribs. Turn ribs over so that the bone side is facing up. Remove the membrane along the back by sliding a dull knife (such as a butter knife) under the membrane along the last bone until you get under the membrane. Hold on tight, and pull it until the whole thing is removed from the rack of ribs.
Rub ribs all over with spice rub. Once fire is ready, place the ribs on indirect heat - the side of the grill that has the foil pan. Cover and cook about 2 hours, watching to make sure the fire is maintained at a steady low temperature, adding charcoal as needed, and rotating the rack of ribs roughly every 30 minutes so that different edges of the rack are turned toward the hot side.
After 1 1/2 to 2 hours, remove ribs and wrap in foil. Return to the grill for another 30 minutes or so.
When ribs are done, you can either remove them from the foil and place back on the grill, meat side down, for a little char, or place them meat side up and brush with barbecue sauce in layers, waiting about 5 minutes between layers. Or simply remove them from the grill to a cutting board, slice, and serve!