Oven-Barbecued Spareribs

1. Combine mustard, ketchup, and garlic in bowl; combine sugar, salt, paprika, chili powder, pepper, and cayenne in separate bowl. Spread mustard mixture in thin, even layer over both sides of ribs; coat both sides with spice mixture, then wrap ribs in plastic and refrigerate for 8 to 24 hours.
2. Transfer ribs from refrigerator to freezer for 45 minutes. Adjust oven racks to lowest and upper-middle positions (at least 5 inches below broiler). Place baking stone on lower rack; heat oven to 500 degrees. Sprinkle ground tea evenly over bottom of rimmed baking sheet; set wire rack in baking sheet. Place ribs meat side up on rack and cover with heavy-duty aluminum foil, crimping edges tightly to seal. Place baking sheet on stone and roast ribs for 30 minutes, then reduce oven temperature to 250 degrees, leaving oven door open for 1 minute to cool. While oven is open, carefully open 1 corner of foil and pour apple juice into bottom of baking sheet; reseal foil. Continue to roast until meat is very tender and begins to pull away from bones, about 1-1⁄2 hours. (Begin to check ribs after 1 hour; leave loosely covered with foil for remaining cooking time.)
3. Remove foil and carefully flip racks bone side up; place baking sheet on upper-middle rack. Turn on broiler; cook ribs until well browned and crispy in spots, 5 to 10 minutes. Flip ribs meat side up and cook until second side is well browned and crispy, 5 to 7 minutes more. Cool for at least 10 minutes before cutting into individual ribs. Serve with barbecue sauce, if desired.

REMOVING THE MEMBRANE FROM THE RIB RACK
1. Insert spoon handle between membrane and ribs to loosen slightly.
2. Using paper towel, grasp loosened membrane and pull away gently to remove.