Preheat your oven to 250 degrees F. Line a baking sheet with aluminum foil and place a wire cooling rack over the foil.
Remove ribs from packaging, rinse, and pat dry with paper towels. On the underside of the ribs, there is a membrane that needs to be removed. Use a paring knife to help separate the membrane from one edge of the rib meat. Once the membrane is started, grip it firmly with your hand and pull it off the meat while you hold the ribs with your other hand. It may come off in sections, just keep working at it until the whole membrane has been removed.
Cut the rack of ribs in half. Place the two halves on top of the cooling rack, bottom side up. Set aside.
In a small mixing bowl, combine the brown sugar, chili powder, brown sugar, paprika, salt, pepper, garlic powder, onion powder, mustard, cumin, and cayenne.
Use your hand to spread one-quarter of the seasoning rub over each of the two rib halves. Rub the seasoning all over the rib meat and bones. Turn the ribs over and spread the remaining rub over the ribs until they are well coated.
Loosely cover the ribs with foil to help keep them moist.
Bake overnight, for 8 to 12 hours. (see temperature notes below) Carefully remove from the oven and remove the foil. Allow ribs to cool to the touch.
Transfer to a cutting board and cut the ribs into serving portions. For dinner, cut each half rack in half again before serving. For appetizers, cut into single bone portions. Serve with your favorite BBQ sauce for dipping, if desired.
You can cook these ribs for 8 hours at 250 degrees F or for 12 hours at 200 degrees F. I find that the longer cooking time has the meat falling off the bone, while the shorter time sticks to the bone a little better...depending on your serving preference.