Flip the ribs so the bone sides are facing up. The key to tender ribs is to remove the membrane (the thin, white silver skin). Slide a butter knife under the membrane to lift a corner, then grab it with a paper towel for a non-slip grip and pull it off. It may come off in one piece or several.
Pat the ribs dry. Slather a thin layer of yellow mustard or olive oil all over the ribs. This helps the rub adhere. Generously season the entire rack, covering the meat side and bone side with Pork rub.
Preheat your smoker to 225°F (107°C). Whether you’re using a pellet grill or a charcoal smoker, set it up for indirect cooking.
Place the seasoned ribs directly on the smoker grate, bone-side down. Let the smoke the ribs for 2 hours, undisturbed.
After 2 hours, remove the ribs from the smoker. Lay out two large sheets of heavy-duty aluminum foil. Place a rack of ribs on each sheet.
Pour about ½ cup of apple juice or a mix of ribs with apple cider vinegar over each rack. This is crucial for keeping them moist.
Wrap the ribs tightly in the foil, ensuring a sealed packet so the steam cannot escape. Place the wrapped ribs back on the smoker, meat-side down.
Let the wrapped baby back ribs in smoker cook for another 2 hours.
Carefully unwrap the ribs (watch for hot steam). They should be very tender. Place them back on the smoker grate, bone-side down. Brush a generous layer of barbecue sauce over the top.
Close the lid and let the ribs cook for another 30 minutes to an hour, or until the sauce is tacky and caramelized.
Remove the ribs from the smoker and let them rest for 10-15 minutes before slicing and serving.