Preheat oven to 80 degrees Celsius. Put refractory shape in the oven. Incise diamond-shape cuts duck breast without cutting the meat. Season with salt and pepper and rub the breast in cuts. Heat the oil in a frying pan, fry the breast skin side down for 3 minutes, turn and cook another 2 minutes. Put into shape and let it for 30 minutes in the oven. Pour any excess fat out of pan and bring to a boil red wine and cherry juice, stirring to mix with the meat juices. Boil and add the cherries. Season with sugar, salt, pepper and lemon juice. If necessary, add the butter. Slice the duck breast and serve with sauce.