Ingredients

• 2 whole racks St. Louis–cut pork ribs (about 2.5 pounds each)
• 1 medium yellow onion, grated
• 1/4 cup (60 ml) dark brown sugar
• 1/3 cup (80 ml) molasses
• 1-1/2 cups (360 ml) ketchup
• 2 tbsp spicy brown mustard
• 1/4 cup (60 ml) Worcestershire sauce
• 1/4 cup (60 ml) apple cider vinegar
• 1/3 cup (80 ml) paprika
• 2 tbsp whole yellow mustard seed
• 2 tbsp garlic powder
• 1 tbsp onion powder
• 1 tbsp dried oregano
• 1 tbsp whole coriander seed
• 1 tsp red pepper flakes
• 1 tsp whole cumin seed
• 1/4 cup (60 ml) kosher salt
• 1 tsp freshly ground black pepper
• 3/4 tsp liquid hickory smoke (Wright's or Colgin)

Steps

1. For the Spice Rub: In a spice grinder, combine paprika, brown sugar, salt, mustard seed, garlic powder, onion powder, oregano, coriander seed, cumin seed, red pepper flakes, and black pepper and reduce to a fine powder, working in batches as needed.
2. For the Sauce (if using): In a medium saucepan, whisk together 3 tablespoons spice rub, grated onion, ketchup, mustard, molasses, Worcestershire sauce, vinegar, and liquid smoke. Bring to a bare simmer over medium-low heat and cook until reduced and thickened, about 20 minutes. Set aside.
3. For the Ribs: Remove the papery membrane on the back of the ribs, using a paper towel or kitchen towel to grip and pull it away in one piece. Rub racks of ribs generously on all sides with about 1 cup (240 ml) of the spice rub mixture. (Set aside 3 tablespoons of spice rub if making dry-style ribs.)
4. Sprinkle ribs all over with 1 teaspoon liquid smoke, then rub in with hands for even coverage. If ribs don't smell smoky enough, sparingly rub in more liquid smoke. Wrap each rib rack in plastic and refrigerate for at least 2 hours and up to 8.
5. Preheat oven to 250°F (120°C) and adjust rack to middle position. Set a wire rack inside a rimmed baking sheet. Remove and discard plastic from the rib racks, then wrap each rib rack in foil, sealing it tightly, and set on prepared baking sheet. Bake ribs for 2 hours. Remove and discard foil. Return ribs to oven, meaty side up, and continue to cook until a toothpick or skewer can be pushed into meat with minimal resistance, about 1 1/2 hours longer. (Cooking times can vary quite a bit depending on the exact size of rib racks and the oven being used.)
6. To Finish: Increase oven temperature to 500°F (260°C). Meanwhile, rub racks with 3 tablespoons spice rub (if making them dry-style) or brush with sauce (if using). Return to oven and cook, meaty side up, until well browned, 5 to 8 minutes. Divide ribs between bones, if desired; serve, passing additional sauce at the table, if using.