Preparing the Ribs
Remove the membrane from the back of the 3 lb rack baby back ribs by sliding a knife under it and pulling it off with a paper towel for grip. Pat the ribs dry. In a bowl, mix 2 tablespoons paprika, 1 tablespoon brown sugar, 1 tablespoon garlic powder, 1 tablespoon onion powder, 1 tablespoon chili powder, 1 teaspoon cayenne pepper (optional), 1 teaspoon dry mustard, 1 teaspoon black pepper, and 1 teaspoon kosher salt. Rub the seasoning generously over both sides of the ribs, pressing it in to form an even coating. Let the ribs sit at room temperature for about 30 minutes or refrigerate for several hours (or overnight) for deeper flavor.
Preparing the Mop Sauce
In a small bowl, whisk together ½ cup apple cider vinegar, 2 tablespoons yellow mustard, 1 tablespoon brown sugar, 1 teaspoon Worcestershire sauce, ½ teaspoon crushed red pepper flakes, ½ teaspoon garlic powder, and salt and pepper to taste. Set aside for basting during cooking.
Cooking the Ribs
Preheat your smoker or oven to 250°F. Place the ribs bone-side down on the grate or a baking rack set over a tray. Cook low and slow for about 2½–3 hours, maintaining steady heat.
Mopping and Developing Flavor
After the first hour, begin brushing or mopping the ribs lightly with the vinegar-mustard sauce every 30–45 minutes. This helps build layers of flavor and keeps the ribs moist.
Finishing the Ribs
Continue cooking until the ribs are tender and the meat has pulled back from the bones, typically around 3–4 hours total. If desired, you can wrap the ribs in foil for the last hour to speed up tenderness, then unwrap for the final 15–20 minutes to firm up the exterior.
Resting and Serving
Remove the ribs from heat and let them rest for about 10 minutes. Slice between the bones and serve warm, optionally with extra mop sauce on the side.
