Preheat your oven to 300°F, placing the oven rack in the middle position. Line a baking sheet with parchment and set aside.
Remove the membrane from the underside of the ribs. Using a sharp paring knife, separate it at the edge of the rack. Then grip the flap tightly with a piece of paper towel (or kitchen towel) and tear it off. Repeat for any remaining sections.
Make the spice rub by combining garlic powder, paprika, salt, pepper, and cumin.
Rub the ribs all over with the spice rub. Then place them meat-side up on the prepared baking sheet. Cover the baking sheet tightly with aluminum foil.
Bake for 3 hours or until the internal temperature reaches 185 deg F.
Remove from the oven and discard the foil.
In a medium bowl, mix all the BBQ sauce ingredients.
Brush the ribs all over with BBQ sauce. Return to the oven to bake for 30 minutes more or until the sauce has set.