Use 10 g butter to grease a deep pan.
Add the mirepoix and season the cleaned and trussed duck.
Place the duck on the mirepoix.
Coat the duck with the remaining butter.
Cover the pan with a tight fitting lid.
Place the pan in the oven 200- 230 degrees Celcius.
Baste occasionally, cook approx. 1 hour.
Remove the lid and continue cooking the duck basting often until tender approx a further half hour.
Remove the duck, cut out the string and keep the duck in a warm place.
Drain off all the fat from the pan.
Deglace with the stock bring to the boil and allow to simmer for a few minutes.
Thicken by gradually adding the arrowroot diluted in a little cold water.
Reboil, correct seasoning, degrease and pass through a strainer.
Thinly remove the zest from one orange and the lemon and cut into fine julienne.
Blanch the julienne of zest for 3-4 min, refresh.
Place the vinegar, sugar and the juice of the lemon and the oranges in a small sauteuse and cook to a light caramel stage.
Add the sauce from the duck.
Bring to the boil, correct seasoning and pass through a strainer.
Add the julienne to the sauce, keep warm.
Remove the legs from the duck, bone out and cut in thin slices.
Carve the duck breasts into thin slices and neatly dress on a serving dish.
Coat with sauce and serve.