Ribs:
1/3 cup packed dark brown sugar
3 tbsp. sweet paprika
2 tsp. mustard powder
½ tsp. celery seed
½ tsp. onion powder
½ tsp. garlic powder
½ tsp. chipotle chile powder
Salt
4 racks (2 to 2 ½ pounds each) St. Louis-style pork ribs
2 cups boiling water
Sauce:
1 can (28-ounce) tomato puree
½ cup packed dark brown sugar
1/3 cup cider vinegar
¼ cup tomato paste
3 tbsp. Worcestershire sauce
1 tbsp. mustard powder
1 tsp. chipotle chile powder
½ tsp. ground allspice
Pepper, to taste
½ cup hot water
Preparation:
Prepare Ribs: In large bowl, combine sugar, paprika, mustard, celery seed, onion powder, garlic powder, chipotle chile powder, and 1 tablespoon salt. In 2 large (17″ by 13″) roasting pans, place ribs. Rub spice mixture all over ribs; arrange ribs overlapping in pans. Cover pans and refrigerate at least 1 hour and up to 1 day.
Prepare Sauce: In 4-quart saucepan, combine tomato puree, sugar, vinegar, tomato paste, Worcestershire sauce, mustard powder, chipotle chile powder, allspice, and ½ teaspoon freshly ground black pepper. Heat to boiling on high, stirring occasionally. Reduce heat to medium-low; cover partially and simmer 45 minutes or until thickened, stirring occasionally. Cool completely in pan. Pour 1 ¼ cups sauce into serving bowl and stir in hot water; reserve. Preheat oven to 350ºF. Uncover ribs and add 1 cup boiling water to each pan. Cover pans tightly with foil. Bake 1 hour 15 minutes to 1 hour 45 minutes or until tender. Uncover ribs and transfer to large serving platter. Prepare outdoor grill for direct grilling on medium. Place ribs on hot grill grate, bone side down, and cook 2 minutes. Brush with sauce in pan and turn ribs over; cook 5 minutes. Repeat brushing and turning 2 more times, cooking ribs an additional 10 minutes. Cut racks into single-rib portions and arrange on platter. Serve immediately with reserved sauce. Serves 12.