FOR THE RIBS AND RUB:

• 6 racks pork ribs (4 to 6 pounds baby back ribs or 6 to 8 pounds spareribs)
  
• ¼ cup paprika
  
• 1 ½ tablespoons freshly ground pepper
  
• 1 ½ tablespoons firmly packed dark brown sugar
  
• 1 tablespoon salt
  
• 1 ½ tablespoons celery salt
  
• 1 ½ tablespoons cayenne pepper
  
• 1 ½ tablespoons garlic powder
  
• 1 ½ tablespoons dry mustard
  
• 1 ½ tablespoons ground cumin

FOR THE MOP SAUCE:

• 2 cups cider vinegar
  
• ½ cup yellow (ballpark) mustard
  
• 2 teaspoons salt

1. Remove the thin skin from the back of each rib rack by pulling it off in a sheet. A kitchen towel will provide a more secure grip. Combine the ingredients for the rub in a small bowl and whisk to mix. Rub two thirds of this mixture over the ribs on both sides, the transfer the ribs to a roasting pan. Cover, refrigerate and let marinate 4 to 8 hours.
2. Set up the grill for indirect cooking method, placing a drip pan directly below the ribs. Preheat grill to a medium cooking temperature
3. Before placing ribs on grill, toss mesquite wood chips that have been soaking in water on the coals or in the smoker box. Oil the grate, then arrange the ribs over the drip pan. Cover and cook for 1 hour.
4. Prepare the mop sauce. Mix together the mustard, vinegar and salt in a bowl and set aside.
5. When the ribs have cooked for an hour, uncover the grill and brush the ribs with the mop sauce. Toss a few more mesquite chips on the coals or in the smoker box and continue cooking the ribs until tender, ½ to 1 hour longer for baby back ribs, a bit longer for spareribs. Ribs are done when the meat has shrunk back from the end of the bones and the meat is very tender. Just prior to removing from grill, apply more of the rub.