First Step: Prepare the Dry Rub and Toast Spices
Start by heating a dry skillet over medium heat. Toast the fennel seeds, coriander seeds, and cumin seeds for about 2-3 minutes until fragrant. This toasting process intensifies the essential oils, giving your grilled St Louis ribs a richer aroma and flavor. After cooling, grind these toasted seeds into a fine powder using a spice grinder or mortar and pestle.
Mix the ground seeds with the brown sugar, smoked paprika, onion powder, garlic powder, dried oregano, dry mustard, cayenne pepper, and optional seasonings (celery salt, kosher salt, black pepper) in a bowl. This homemade spice rub is key to developing the distinct taste of the ribs.

Second Step: Prepare the Ribs
Remove the silver membrane from the back of the ribs; this is important to allow the rub and smoke to penetrate the meat fully. For guidance on membrane removal, check out tips for removing rib membrane easily.
Coat both sides of the ribs evenly with yellow or Dijon mustard. This acts as a binder, helping your dry rub stick better while tenderizing the meat during grilling.
Apply the dry rub liberally over all sides of the ribs, making sure each inch is covered. For the best flavor, let the ribs marinate in the fridge for 30 minutes up to 8 hours, allowing the spices to infuse deeply.

Third Step: Set Up Your Grill for Indirect Heat
Preheat your grill to around 350°F (175°C). Arrange your coals or burners so that heat is only on one side or half the grill, creating an indirect grilling zone. Clean and oil your grill grates to prevent sticking.
Place the ribs bone side down on the cooler side of the grill. Cover and grill for 30 minutes, ensuring the ribs cook gently without direct flame contact.

Fourth Step: Wrap and Steam the Ribs
Carefully remove the ribs from the grill onto a large sheet of aluminum foil with raised edges. Pour 1/4 cup apple juice or apple cider vinegar over the ribs to add moisture and steam as they cook further.
Wrap the foil tightly around the ribs to seal in moisture. Return the foil packet to the grill over indirect heat, increasing temperature to 375°F (190°C). Cook wrapped for 30 to 45 minutes. This steaming step ensures tender, juicy ribs.

Fifth Step: Final Unwrapped Grill and Baste
Unwrap the ribs and place them back on the grill over indirect heat. Lower the temperature to 250°F (120°C). Baste the ribs generously with barbecue sauce every 15 minutes over approximately 60 minutes. This slow, sauced finish creates a moist, flavorful glaze and tender texture.
Cook the ribs until the internal temperature reaches about 195°F (90°C) for the ideal fall-off-the-bone tenderness. Temperatures as low as 175°F (79°C) are acceptable but may yield slightly firmer meat.

Final Step: Rest and Serve
Take the ribs off the grill and let them rest uncovered for 10 to 15 minutes. Resting lets the juices redistribute, ensuring each bite is juicy and satisfying.
Slice the ribs and serve with extra barbecue sauce on the side. Consider pairing with classic sides or your favorite fresh vegetables for a complete meal.