Remove the thin skin that lines the back of each rib and discard. Place remaining ingredients in a small bowl and stir to combine. Coat ribs evenly with rub on both sides, cover and refrigerate overnight.
Heat the oven to 325°F. Cover each rack separately in their own foil packet and place both racks side-by-side on a baking sheet. If you don't have a baking sheet big enough to fit both racks together, use two baking sheets.
Bake ribs 45 minutes. Open the foil packets and spread the foil out so it covers the baking sheet. Bake the ribs uncovered another 45 minutes or until tender enough that a fork easily penetrates the meat and it's caramelized and browned.
Slice racks of ribs in half for four generous portions or slice each rib individually for an appetizer. Serve with barbecue sauce and lots of napkins.