I have never made duck before. That being said, it is a good idea to do some research on how to cook the particular duck you're preparing. The particular breast I was preparing weighed a pound itself (it was a magret duck breast). Through my research, it indicated it should be served medium rare. I'm glad I researched, because my instinct was to cook it longer. It was quite large. The prep was easy (marinated overnight); in place of the sage leaves, I used the ground sage that I had which imparted the same flavor. We each LOVED the sauce, which was a nice side for the finished dish. My DH & DD loved it all. It was somewhat "gamey" for me alone, but with the sauce, it was very good. It is supposed to be served in thin slices (according to my references, like you would a tenderloin of beef. Served with steamed rice florentine, fried yellow squash and tomatoes. Had intended to take a picture, but they both gobbled it down so quickly, I didn't have a chance.
This recipe is so pefect the vinegar and the mustard add some bite while the honey and the buttermilk mellow it out.