Preheat oven to 400 degrees.  Season duck with salt and pepper.  Heat ovenproof pan on high heat and place duck breast, skin side down.  Reduce heat to medium/high and cook until skin is browned, or about 7 minutes.  Discard all but 2-3 tbsp. of the duck fat from the pan.  Turn duck over and transfer the ovenproof pan to the oven.  Roast 5-7 minutes for medium rare.  Let duck rest before cutting.  While duck is resting bring orange juice, maple syrup, mirin, shoyu and zest, plus 1/4 cup of the duck juice from the pan to a boil.  Cook until reduced by half.  Slice duck breast into 1/4 inch medallions.  Lay 3-4 medallions on top of Celery Root Puree (see above recipe) and drizzle with Orange Maple Glaze.