Heat oven to 375ºF and place rack in lower third. In a small saucepan, heat 1 cup broth and 2 tablespoon butter until butter is melted; set aside.

Remove giblets from turkey and reserve neck bone. Rinse turkey if desired and pat dry. Place in a roasting pan with a rack and tuck back wings. Sprinkle body cavity with ½ teaspoon salt and ½ teaspoon pepper; fill with onion, carrot, orange and herb sprigs. Fill neck cavity with onion and orange, if desired; secure skin flap under turkey. Place any remaining vegetables in bottom of pan with neck bone and ¼ cup broth. Rub turkey with remaining 1 tablespoon butter, 1½ teaspoon salt and ½ teaspoon pepper. Tie legs together.

Cover pan with heavy-duty foil and seal around edges. Roast 1 hr. Reduce oven to 325ºF and roast 1 hr more. Remove foil and roast, basting with broth-butter mixture every 30 to 40 min, until an instant-read thermometer inserted 2 inches into inner thigh (without touching bone) registers 170ºF, 2 to 2½ hrs. Remove turkey from oven, tent with foil and let stand 15 to 45 min before carving. Transfer turkey to a serving platter and remove rack from pan.

For gravy, remove vegetables and neck bone from pan, then strain drippings into a fat separator; pour off fat. Place roasting pan over 2 burners, add wine and heat over medium-high heat to deglaze, scraping up any brown bits in a pan. Stir in pan drippings and transfer to a medium saucepan. Add 2 cups broth and bring to a boil. Stir together remaining 1 cup broth and the cornstarch; whisk into saucepan. Simmer, whisking constantly, until thickened, about 2 min. Transfer to a bowl and serve with turkey.