Prepare the duck

• Pat the duck dry and score the skin of the breasts and legs.
• Season generously inside and out with salt and pepper.
• Rub the orange zest over the skin and place the duck on a rack in a baking dish.

Roast the duck

• Roast in the oven at 180 °C, breast side up.
• Baste regularly with the rendered fat until the skin is golden and crisp.

Make the orange sauce

• Caramelize the sugar in a saucepan until amber.
• Deglaze with the red wine vinegar and orange juice.
• Add the chicken stock and reduce by half.

Finish the sauce

• Stir in the Grand Marnier and simmer briefly.
• Thicken with cornstarch dissolved in a little cold water.
• Off the heat, whisk in the cold butter until glossy.

Rest and serve

• Let the duck rest before carving.
• Carve and serve with the orange sauce and orange segments.