Remove the neck and giblets from the cavity of the duck, pat dry and reserve.

Cut the last two joints of the wings off and reserve. Remove the excess fat from the cavity of the duck and cut off the flap of skin at the back end of the duck. Rinse the duck under cold water and pat dry with paper towels.

Using the tip of a paring knife, prick the duck all over, in 1/2-inch intervals, inserting the knife at an angle to pierce just the skin, not the flesh.

Make sure to prick the skin around the leg thigh joint thoroughly, as there is a lot of fat stored there. Season the duck well with salt and pepper. Place on a rack in a roasting pan and roast on the oven's middle shelf for 3 1/2 hours, removing the roasting pan after the first and second hour of roasting to re-prick the duck skin.

Carefully pour off all the fat in the roasting pan, and increase the oven temperature to 450 F. Return the duck to the oven and roast it for 10 minutes.

Transfer the duck to a platter, cover with foil, then let it rest for 30 minutes before carving. While the duck is roasting, cut the neck and wings into 1 1/2-inch pieces. In a large saucepan over medium-high, heat the vegetable oil. Add the neck, giblets and wings. Cook, stirring often, until golden brown, 8 to 10 minutes. Reduce the heat to medium and add the onion, carrot and garlic. Cook until the vegetables are lightly browned, 5 to 8 minutes.

Add the tomato paste and cook, stirring, for 1 minute. Add the wine and bring to a boil, stirring to pick up any browned bits on the bottom of the pan. Boil until most of the wine has evaporated. Add the celery, thyme, bay leaf, broth and 1 cup water. Bring to a boil, reduce to a simmer and cook, skimming off any scum that rises to the surface and adding water to the saucepan if the liquid dips below the bones, until the duck is ready to come out of the oven. While the duck is resting, strain the stock and discard the solids. You should have about 1 1/2 cups of liquid; if you have more, boil it down. If you have less, add water. In a small bowl, whisk together the flour and 1/4 cup water. In the saucepan, bring the duck stock to a boil, add the flour mixture in a stream, whisking. Bring the mixture back to a boil and simmer 4 minutes. Stir in the green peppercorns and mustard, then season the sauce with salt and pepper. Carve the duck and serve with sauce.

Sara Moulton is host of US public television's Sara's Weeknight Meals. Her latest cookbook is Home Cooking 101.