Fill the charcoal chimney half full with briquettes and only light a handful of them to ensure the pile burns slowly. Place the briquettes in a pile against one side of the grill. Add 3 chunks of smoking wood, such as cherry, if desired.
Set cooking grate on grill and place foil pan on the grate over charcoal. Fill pan halfway with water.
Remove membrane from under the ribs by sticking a butter knife in-between membrane and bone. Gently work the knife around to loosen the membrane and pull completely off. Using a paper towel for added grip works well.
Rub mustard around both sides of the ribs and generously apply rib rub. If not using a rib rub simply season with salt.
Set rack of ribs on far side of the grill away from coals and cook at 225 - 250 degrees. Cover grill and cook for 3 hours if using spareribs, cook 2 hours if using Baby Back Ribs.
After 3 hours, wrap ribs in foil, adding 2 tablespoons of liquid, such as apple juice, and seal tightly. Add another half chimney of charcoal if needed and cook for an additional 2 hours with grill covered.
Unwrap the ribs and discard the foil. Flip the ribs upside down and paint the bottom of the ribs with BBQ sauce. Cover grill and cook for 15 minutes.
Flip ribs back upright and paint top of ribs with BBQ sauce. Cover and continue cooking for 45 minutes.
Remove ribs from the grill, let cool slightly and enjoy!