1. Prepare the ribs: Place 1 rib rack, meat side down, on a work surface. With a knife, cut a small slit through the silvery membrane at 1 end of the rack. Using a paper towel, grip the cut portion of the membrane, gently peel it from the rack, and discard. Repeat with remaining rack.

2. Make the rub: Combine sugar, salt, pepper, paprika, mustard powder, and celery seed in a bowl. (If mixture is clumpy, pass through a medium sieve.) Rub mixture on both sides of each rack. Place ribs on a rimmed baking sheet, cover, and refrigerate for at least 2 hours (or overnight). Let stand at room temperature for 30 minutes before cooking.

3. Make the sauce: Heat oil in a medium saucepan over medium heat. Add onion and garlic, and cook until onion is tender, 2 to 3 minutes. Add red-pepper flakes and tomato paste, and cook for 1 minute. Stir in bourbon, scraping the pan. Stir in tomatoes, vinegar, Worcestershire sauce, water, and sugar, and cook, continuing to stir, until sugar dissolves.

4. Simmer the sauce: Bring the sauce to a boil. Reduce heat, and simmer until reduced by 1/3, about 30 minutes. Season with salt and pepper. Let cool slightly. Puree in a blender until smooth. (You should have about 2 cups.) Use immediately, or let cool completely, cover, and refrigerate for up to 2 weeks.

5. Set up the grill: Place a 9-by-13-inch disposable aluminum pan in the center of bottom grill rack. If using a charcoal grill, place a chimney starter on top grill rack, and fill with about 60 charcoal briquettes (about 4 pounds). Stuff newspaper under chimney, and ignite. Heat briquettes until just covered in ash. Wearing oven mitts, carefully lift chimney, remove top rack, and pour coals onto bottom rack along both sides of pan. Top coals with 1 to 2 chunks hardwood or 1 cup wood chips that have been soaked in water for 1 hour and drained. Fill pan halfway with hot water. Replace top rack. If using a gas grill, heat to medium-low.

6. Grill the ribs: Let ribs stand at room temperature for 30 minutes before cooking. Fold a paper towel into a thick rectangle, and dip it in oil. Hold towel with tongs, and brush oil on top grill rack. Place both rib racks, bone side down, on top grill rack, directly over pan. Cover, keeping top grill vents halfway open and bottom vents completely open to maintain grill temperature of 275 degrees to 325 degrees. Cook ribs, without turning, until the meat is tender but not falling off bones, and has shrunk 1/2 inch from ends, 3 to 3 1/2 hours, adding 8 briquettes to each charcoal pile every hour.

7. Baste the ribs: Transfer 1 cup sauce to a small serving bowl. Brush both sides of ribs with remaining 1 cup sauce. Cover, and grill until ribs are glistening and deep mahogany, about 15 minutes. Let stand for 10 minutes. Serve with reserved sauce.