Duck in Orange Sauce

Ingredients: for four people

2 young ducks.
1 kg of potatoes
1/2 litre of duck stock
juice of four oranges, plus the zest from two of them, sliced finely to decorate
sugar
mandarin vinegar
oil

Rub the ducks on the inside and outside with salt and pepper. Place them in a roasting pan and put it in an oven that has been preheated to 250 degrees Celsius.
Let roast for 35 minutes or longer, turning several times so that each duck browns evenly.

The sauce

Cut the neck of the duck into several pieces and fry gently in butter. Add the mandarin vinegar, the juice of 4 oranges and two tablespoons of sugar to taste. Simmer for around twenty minutes, then pass through a fine sieve. Stir in a knob of butter.

The potatoes

Cut the potatoes into 3 mm slices.
Blanch them in oil at 140 degrees Celsius without letting them brown.
Remove the potatoes, heat the oil further to 180 degrees and put the potatoes back in until they are slightly brown. The increased heat will cause the potatoes to puff up. Leave them in till they brown slightly.