Rinse the ribs under cold running water and blot dry with paper towels. Combine the paprika, hot pepper flakes, mustard seeds, 2 teaspoons coarse salt, pepper, brown sugar, celery salt, garlic powder, onion powder, dried oregano, and cumin in a small bowl or spice shaker. Set aside 2 tablespoons for the mop sauce. Sprinkle about 1 tablespoon of the rub on the meat side a