Make the dry rub by combining all the ingredients in a small bowl and stir to combine.

Next, prepare the ribs by removing the membrane on the back of the ribs.

Add a layer of mustard on each side of the rib, about one tablespoon on one side, or enough to evenly coat it. Sprinkle on 1/4 of the dry rub and then rub it around to ensure it is evenly coated. Repeat on the front and back of each rack of ribs. 

Tightly wrap each rack of ribs with foil. If the ribs are thicker you may need to use more than one piece. Add the ribs to the fridge and let them marinate for 1-4 hours. 

When you are ready to bake, preheat the oven to 275 degrees F. Add to the ribs to the preheated oven and bake for 3 to 3.5 hours.

Check the ribs at 3 hours. Take a fork to test how tender they are. If the meat easily comes apart it is ready, if it doesn't come apart yet, wrap it back up tightly and bake for another 30 minutes. If it still isn't falling apart at 3.5 hours let it bake for 20 more minutes and test again.

When the meat is tender, remove from the oven and turn the oven to the broil setting on high. Open the foil up and then drizzle BBQ sauce on top of the ribs, enough to give it a good coating. Add the ribs to the oven on the middle rack on broil to let the BBQ sauce caramelize. Broil for 5 minutes, and keep a close eye on it because it can easily burn on the broil setting. 

Let the rack of ribs rest for 15 minutes and then slice and serve.