Remove the thin membrane from the back of each rib rack. Slide a butter knife under the membrane at one end, then grip with a paper towel and pull it off.

Mix the salt, smoked paprika, garlic powder, black pepper, and cayenne in a small bowl. This is your dry brine/rub.

Pat the ribs dry with paper towels. Rub the dry brine mixture all over both sides of the racks. Place on a baking sheet, cover loosely with plastic wrap, and refrigerate for at least 1 hour (up to 12 hours).

About 30 minutes before grilling, remove ribs from the fridge to come to room temperature.

Prepare a two-zone fire in a charcoal grill: fill a chimney starter with charcoal, light it, and let burn until coals are covered with gray ash. Pour the hot coals onto one side of the grill only. Leave the other side empty. Place a drip pan on the empty side.

Aim for a grill temperature of 225-250°F (107-121°C) on the indirect side. Adjust the vents to control airflow—open vents raise temp, closed vents lower it.

Once the grill is stable, place the ribs bone-side down on the grate over the drip pan (the cool side). Close the lid.

Cook for 2 hours, maintaining the temperature. Add 5-6 unlit charcoal briquettes every 45 minutes to keep the fire steady. Do not lift the lid more than necessary.

After 2 hours, mix the apple cider vinegar and water in the spray bottle. Spritz the ribs lightly every 20 minutes for the next 30 minutes.

Check for doneness: the internal temperature should be around 195-203°F (90-95°C) between the bones. Another test: pick up the rack with tongs at one end—it should bend and the meat should start to crack on the surface. If it's still stiff, cook another 15-20 minutes.

Optional: for a glazed finish, brush your favorite BBQ sauce onto the ribs during the last 10 minutes of cooking. Let the sauce set over the heat.

Remove ribs from the grill, wrap loosely in foil, and rest for 10 minutes before slicing between the bones. Serve hot.