Prick the duck all over with a fork and
place on a rack over a roasting tin.
Roast the duck in a preheated oven, 180oC
(350oC), Gas Mark 4 for about 1 1/2 hours, until tender.
Meanwhile, make the marinade. Combine the
garlic, ginger, five spice powder, chili sauce and groundnut oil in a
bowl.
Allow the duck to cool and then cut in
half down the backbone, using a cleaver or poultry shears.
Remove the ribs and backbone. Place the
duck on a dish and cover it with the marinade. Cover and refrigerate
overnight.
Put the duck, skin side up, on a wire rack
over a roasting tin. Roast, uncovered in a preheated oven, 200oC
(400oF), Gas Mark 6, for about 35 minutes until the skin is
crisp.
While the duck is roasting, simmer all the
ingredients for the ginger sauce in a saucepan until reduced to about
half.
Strain and return to the pan.
Serve the duck sprinkled with spring
onions and with the sauce poured around it.