Duck in orange sauce

Preparation:

Preparation: Salt and pepper the duck and brown it in 30 g of butter for 10 minutes, then remove it, remove the bottom, add the remaining butter, add the duck again, cover and cook over low heat for 30 minutes. Wet with 10 cl of cognac and cook for another 30 minutes. Dissolve 1 tablespoon of sugar in 1 tablespoon of vinegar, add the filtered cooking juices, 10 cl of orange liqueur, the lemon juice and 5 oranges, julienned peel and the slices of 1 orange and cook for 10 minutes. Sprinkle the duck cut into pieces and serve hot.