Prepare the ribs. Pat the ribs dry. On the bone side, slide a butter knife under the thin membrane at one end, grip it with a paper towel, and pull it off.
Rub. Mix the rub ingredients and press them all over both sides of the ribs. Wrap and refrigerate at least 1 hour, or overnight.
Bake low and slow. Heat the oven to 300°F. Wrap each rack tightly in heavy-duty foil, meat side up, and place on a rimmed sheet pan. Bake 2 hours 30 minutes, until the meat is very tender and pulling back from the bones.
Make the sauce. While the ribs bake, simmer all sauce ingredients in a small saucepan over medium-low heat, stirring, for 10 to 15 minutes, until slightly thickened. Set aside.
Glaze. Increase the oven to 425°F. Carefully open the foil, pour off the juices, and move the ribs, meat side up, to a foil-lined sheet pan. Brush generously with sauce. Bake 10 minutes, brush again, and bake 5 to 10 minutes more, until sticky and caramelized. For extra char, broil 1 to 2 minutes, watching closely.
Rest and serve. Rest the ribs 10 minutes, then cut between the bones. Brush with a final thin coat of sauce and serve with extra sauce on the side.