Before roasting, boiling water is poured over the duck. This tightens the skin and seals the pores so that the skin will be crisp when cooked.
Trim away the excess fat from the tail end of the duck. Cut a long piece of kitchen string and tie it in a double knot around the fat at the neck end of the duck.
Bring about 2 litres water to the boil in a wok. Hold the duck in the water and ladle it over the duck until the skin becomes taut. Remove the duck and pat dry.
Hang the duck over dish to catch the Leave in a cool (10°C), place until the skin is dry, about 3 hours.