Yield: 4 to 6 servings
2 tablespoons kosher salt
2 tablespoons smoked paprika
2 tablespoons firmly packed light brown sugar
1 tablespoon sugar
1 tablespoon ground black pepper
2 teaspoons dried oregano
2 teaspoons ground mustard
1 teaspoon garlic powder
1 teaspoon onion powder
1 teaspoon dried thyme leaves
1 teaspoon ground cumin
1 teaspoon celery seeds
½ teaspoon ground red pepper
1 cup water
¼ cup apple-cider vinegar
2 (3½-pound) racks St. Louis–style pork spare ribs
1. In a medium bowl, combine salt, paprika, brown sugar, sugar, black pepper, oregano, mustard, garlic powder, onion powder, thyme, cumin, celery seeds, and red pepper.
2. Place 2 tablespoons spice mixture in a small bowl; add 1 cup water and apple-cider vinegar, whisking to combine to create mopping sauce. Set mixture aside.
3. Rinse ribs and pat dry. Remove thin membrane from back of ribs by piercing it with a sharp knife and pulling it off. Rub salt mixture evenly over ribs. Let stand at room temperature for 30 minutes.
4. Preheat one side of grill to medium-low (250° to 300°).
5. Grill ribs, meaty side down, over indirect heat, with grill lid closed, for 2 hours, brushing ribs every 30 minutes with mopping sauce. Turn ribs over, and cook for 3 to 4 hours, brushing every 30 minutes with mopping sauce. Cook until meat is very tender. Serve immediately.