To prepare the duck, make a small hole in skin and blow up the poor beast with a compressor or a drinking straw. This lifts the skin, so that the fat underneath will drain out when cooking and the skin will become beautifully crisp. Cut off the neck and wing tips.
Make a thick syrup by boiling the sugar, honey and 300 ml water together. Then add the ginger and cardamom, together with a little liquorice if you can find it! Paint the syrup on the duck and hang it in a cool, airy place (not the fridge) until the end of the day. Keep painting it with the syrup whenever you think about it.
Preheat the oven to 180°C/Gas 4. Place the duck on a rack over a roasting tin filled with water. Cook the duck until it is well roasted and caramelized, about 1½-2 hours.
To make the sauce, brown the duck neck and wings in a little oil, then add the onion, celery and carrots, and fry gently for a few minutes. Make a stock by adding the giblets, together with the ginger and cardamom taken from the sugar syrup and 300 ml water. Boil for several hours until it has reduced by half, strain off and skim any fat from the top. Now add the soy sauce, dry sherry and finally the unsweetened or very dark chocolate to taste. This is the most critical part of the recipe – add the chocolate little by little and stop when you can discern the bitterness. If it needs to be thickened, add a little cornflour mixed with cold water, and boil until the sauce is no longer cloudy.