Method
Score the duck skin in a criss-cross pattern.
Season with salt and pepper. Prepare sauce Pour syrup into a small pot and heat for about 1 minute. Add cider vinegar and finely chopped shallot. Cook for 1 minute more. Add the duck stock or commercial sauce. Simmer until sauce reduces down to the desired consistency. Add the buckthorns and simmer for 5 minutes. Strain the syrup and press down on the buckthorns with a soup ladle. Season to taste. Keep sauce warm.
Method
Preheat oven to 180°C (350°F). Heat a heavy bottomed baking dish, do not add any fat. When the dish, is hot, starting with the skin side, sear duck breasts on both sides until they are nicely browned. Roast for about 5 minutes or until meat is pink. Remove from oven and tent with aluminum foil. Finishing and presentation Allow breasts to rest for 5 minutes before slicing. Arrange slices on a warm platem mask with sauce and serve a vegetable side dish.
Reference: http://www.argousier.qc.ca