Start by scoring the skin. Use a sharp knife and cut a cross-hatch pattern with a little over 1/2" spacing. Make sure you cut through the skin and the layer of fat just beneath, but don't cut into the meat. Start by cutting parallel lines in one direction, then rotate the meat 90° and do the same again.
Apply the rub on all sides, including the skin. Leave the meat in the fridge for a few hours, or even better, overnight.
Fire up the grill, prepare it for indirect heat. Try to keep it at 150° C / 300° F. Place a few chunks of wood on the glowing embers for smoke flavor. Place the pork belly on the grates and close the lid. Smoke it for approximately 2 hours, it is done when the meat temp is 75° C / 167° F.
Now remove the meat from the grill and open all vents and stoke that fire. We want it to get real hot.
When the grill is up to temp, place the pork belly on the grates, skin side down. Check it often (every 30-60 seconds) until the skin is 'popped'. It usually doesn't take long. You know it's done when many blisters have formed on the skin, making the surface uneven. But watch it so it doesn't go all black and burnt.
Now bring the meat in, and let it rest for 15 minutes before slicing and serving. Sprinkle liberal amounts of chive all over and enjoy a great tasting pork belly!