1. Preheat oven to 300°F.
2. In a small bowl combine the brown sugar, salt, smoked paprika, garlic powder, mustard powder, cumin, and crushed red pepper flakes, if using.
3. Optional Step: Remove the membrane from the bone side of the ribs. If you don’t know how to do this, check out the video link in the article above. 
4. Lay each rack of ribs on a large piece of aluminum foil. Sprinkled each side of each rack with ¼ of the rub mixture. Wrap each rack tightly in the foil making sure the scrunched up folded seam is along the top of the racks. Lay each foil wrapped rack seam side up on another large piece of foil and wrap tightly with the seam along the top again.
5. Put the ribs onto a large pan with a lip to catch any juices that escape. Put the pan into the preheated oven.
6. Cook baby backs for 1.5-2 hours, St. Louis spare ribs for 2-2.5 hours. The shorter cooking time will fully cook the ribs and get them tender but still hugging the bone. The longer cooking time will yield ribs that fall off the bone.
7. Remove pan from oven and allow ribs to cool for 15 minutes (this sets the juices making it easier to cut the ribs and helping the meat stay on the bone when you grill). Proceed or transfer ribs to the fridge overnight.
8. Carefully unwrap the ribs. Transfer the racks to a cutting board.
9. Preheat your grill for direct grilling over medium-high heat.*
10. Cut the ribs into servings with 1-2 bones each. Brush each serving liberally with sauce. Put the ribs on the grill for 5-7 minutes turning occasionally. All you’re doing is heating them up and getting a bit of char here and there. Taste one to see if it’s heated through ;)

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