Remove the duck from the packaging and pat dry inside and out with paper towelling. Place the duck on a tray lined with a rack uncovered. Air dry in the fridge overnight.
Preheat the oven to 190°C. Season the duck with salt. Roast for 40 minutes per kilo and until golden and crisp.Remove duck from the oven and let it rest for 20 - 30 minutes.
While the duck is cooling, make the sauce. Bring a small saucepan of water to the boil and cook orange peel for 10 minutes. Drain well. In a saucepan on low heat, add the cranberries and jelly and bring to the boil, add the port followed by add the shallots, the juice and mustard. Add a pinch of cayenne pepper and ginger powder and some salt to taste and for 15 minutes to reduce. Add the butter and fold through.