1. Combine mustard, ketchup, and garlic in small bowl; combine remaining rub ingredients in separate small bowl. Spread mustard mixture in thin, even layer all over inside and outside of duck, then coat all over with spice mixture. Wrap duck in plastic and refrigerate for at least 8 hours and up to 48 hours.

2. Using tip of paring knife or sharp scissors, cut many nicks in skin over entire body of duck. Set V-rack inside large roasting pan. Place duck quarters, skin side up, on rack. Place roasting pan over 2 burners and add enough water to come just below bottom of duck. Bring water to boil over high heat, cover tightly with aluminum foil, and adjust heat to medium. Steam, adding more hot water to maintain water level, if necessary, until fat beads on pores of duck and bird is partially cooked, 30 minutes. Lift duck from rack, use paper towels to pat skin gently (so as not to break it) to remove excess fat and moisture.

3. Adjust oven rack to lowest position and place baking stone on lower rack; heat oven to 500°F. Sprinkle ground tea evenly over bottom of foil-lined rimmed baking sheet; set wire rack on sheet. Place duck pieces skin side up on rack and cover with heavy-duty foil, crimping edges tightly to seal. Roast duck directly on stone for 10 minutes, then carefully open one corner of foil and pour apple juice into bottom of baking sheet, remove breast pieces to cutting board, and reseal foil. Reduce oven temperature to 250°F, leaving oven door open for 1 minute to cool. Continue to roast until meat is very tender and begins to pull away from bones, about 45 minutes.

4. Remove foil carefully. Turn on broiler; transfer all pieces (including breasts) to baking sheet, and place on lower oven rack. Cook until well browned and crispy, 8 to 10 minutes. Cool for at least 20 minutes before carving. Serve with barbecue sauce, if desired.

Serves 2 as a main course or 4 as a first course