Spiced Roasted Turkey

Ingredients:
1 teaspoon black peppercorns
1 teaspoon Sichuan peppercorns
1 teaspoon coriander seeds
2 whole cloves
1/2 teaspoon star anise pieces
4 teaspoons coarse sea salt
2 tablespoons finely grated (with a Microplane) peeled ginger (a 5-inch piece)
2 tablespoons finely grated (with a Microplane) garlic (8 cloves)
2 tablespoons unsalted butter, softened
1 (14-pound) turkey at room temperature 1 hour, any feathers and quills removed with tweezers or needlenose pliers, reserving neck and giblets (discard liver)
2 tablespoons vegetable oil
2 bunches scallions, coarsely chopped
2 carrots, coarsely chopped
2 celery ribs, coarsely chopped
6 (1/4-inch-thick) slices fresh ginger
1 cup Chinese rice wine, such as Shaoxing, or medium-dry Sherry
4 to 5 cups reduced-sodium chicken broth
1 tablespoon soy sauce
3 tablespoons cornstarch
Equipment: an electric coffee/spice grinder; kitchen string; a V-shaped roasting rack; a 17- by 14-inch roasting pan; a 1-quart measuring cup; a fat separator (optional)
kitchen string
1 V-shaped roasting rack
1 17- by 14-inch roasting pan
1 1-quart measuring cup
1 fat separator

Instructions:
Preheat oven to 450°F with rack in lowest position.
Toast spices with sea salt in a dry small heavy skillet over medium-low heat, stirring occasionally, until fragrant and coriander is a shade darker, 8 to 10 minutes. Transfer to grinder and pulse until finely ground. Reserve 1 teaspoon spice mixture, then stir together remaining spice mixture with grated ginger, garlic, and butter to form a paste.
Rinse turkey inside and out, then pat dry. Fold neck skin under body. Starting at large cavity end of turkey, gently slide your fingers between skin and flesh of breast and legs to loosen skin, being careful not to tear skin. Using a spoon, slide spice paste under skin of turkey breast and legs, pushing butter out of spoon with a finger on outside of skin (do not put spice paste under turkey skin in advance). Tie drumsticks together with kitchen string and tuck wings under body.
Pat giblets and neck pieces dry and cut into 1-inch pieces. Heat vegetable oil in a 12-inch heavy skillet over medium-high heat until it shimmers, then sauté giblets and neck pieces, stirring occasionally, until golden, about 5 minutes. Add scallions, carrots, celery, and sliced ginger and sauté, stirring, until lightly browned, about 8 minutes.
Add rice wine and boil, stirring and scraping up any brown bits, 1 minute. Stir in 4 cups broth, soy sauce, and reserved teaspoon spice mixture and bring to a boil. Pour mixture into roasting pan, then set rack in roasting pan, arranging neck pieces and vegetables around rack as necessary (liquid should be just below bottom of rack).
Roast turkey on rack, rotating pan 180 degrees halfway through roasting, until an instant-read thermometer inserted into fleshy part of thighs (test both, close to but not touching bone) registers 170°F, 1 1/2 to 2 hours.
Carefully tilt turkey so juices from inside large cavity run into roasting pan, then transfer turkey to a platter, reserving juices in roasting pan. Let turkey stand, uncovered, 30 minutes (temperature of thigh meat will rise to 175°F).
Strain pan juices through a large fine-mesh sieve into 1-quart measure, pressing hard on and then discarding solids, and let stand until fat rises to top. Skim off and discard fat. (If using a fat separator, pour pan juices through sieve into separator and let stand until fat rises to top, 1 to 2 minutes. Carefully pour pan juices from separator into measuring cup, discarding fat.) You should have 4 cups stock. If there is less, add more broth. If there's more, boil to reduce. Transfer all but 1/2 cup stock to a heavy medium saucepan and bring to a boil.
Whisk together cornstarch and 1/2 cup reserved stock in a small bowl until smooth, then whisk into boiling stock and boil, whisking occasionally, 2 minutes. Serve turkey with gravy.