Spread dijon mustard across both sides of the ribs.
Then rub in the rib rub across both sides.
Wrap in foil and place in fridge overnight (or at least 8 hours).
On a gas grill, heat all your burners, and let heat to around 400 degrees, then turn off all but outer two burners.
Place ribs, meat side up, directly in the middle of grill and close the lid.
Using a thermometer, make sure to keep the temperature around 250 degrees and cook for 5 hours. Try not to open the grill while cooking so heat doesn't escape.
After 2 1/2 hours, open grill and rotate 180 degrees, cook another 2 1/2 hours.
The last 30 minutes of cooking, turn all you burns up to 350 degrees and generously brush the ribs with the BBQ sauce, on both sides, every 5-10 minutes (do this at least 5 times). Remove from the grill and serve immediately.