1 tablespoon kosher salt
1 teaspoon ground coriander
1/2 teaspoon ground cumin
1 teaspoon black pepper
1 (5- to 6-lb) Long Island duck (also called Pekin)
1 juice orange, halved
4 fresh thyme sprigs
4 fresh marjoram sprigs
2 fresh flat-leaf parsley sprigs
1 small onion, cut into 8 wedges
1/2 cup dry white wine
1/2 cup duck stock, duck and veal stock*, chicken stock, or reduced-sodium chicken broth
4-5 medium carrots
4-5 medium red potatoes, cleaned, skin on, quartered
1/4 cup sugar
1/3 cup fresh orange juice (from 1 to 2 oranges)
2 tablespoons white-wine vinegar
1/8 teaspoon salt
1 cup duck or chicken stock or reduced-sodium chicken broth
1 tablespoon unsalted butter, softened
1 tablespoon all-purpose flour
1 tablespoon fine julienne of fresh orange zest, removed with a vegetable peeler
Put oven rack in middle position and preheat oven to 475°F.
Stir together salt, coriander, cumin, and pepper. Pat duck dry and sprinkle inside and out with spice mixture. Cut 1 half of orange into quarters and put in duck cavity with thyme, marjoram, parsley, and 4 onion wedges.
Squeeze juice from remaining half of orange and stir together with wine and stock. Set aside.
Spread remaining 12 onion wedges in roasting pan with carrot and potatoes, then place duck on top of vegetables and roast 30 minutes.
Pour wine mixture into roasting pan and reduce oven temperature to 350°F. Continue to roast duck until thermometer inserted into a thigh (close to but not touching bone) registers 170°F, 1 to 1 1/4 hours more. Turn on broiler and broil duck 3 to 4 inches from heat until top is golden brown, about 3 minutes.
Tilt duck to drain juices from cavity into pan and transfer duck to a cutting board, reserving juices in pan. Let duck stand 15 minutes.
While duck roasts, cook sugar in a dry 1-quart heavy saucepan over moderate heat, undisturbed, until it begins to melt. Continue to cook, stirring occasionally with a fork, until sugar melts into a deep golden caramel. Add orange juice, vinegar, and salt (use caution; mixture will bubble and steam vigorously) and simmer over low heat, stirring occasionally, until caramel is dissolved. Remove syrup from heat.
Add 1 cup stock to pan.
Stir together butter and flour to form a beurre manié. Bring pan juices to a simmer in a 1- to 2-quart heavy saucepan, then add beurre manié, whisking constantly to prevent lumps. Add orange syrup and zest and simmer, whisking occasionally, until sauce is thickened slightly and zest is tender, about 5 minutes. Serve with duck.