Take the refrigerated duck breast fillet to a cutting board. On the fat side, slice dense cross cuts with a sharp knife. The cuts should go deep, right on the meat.
Rub the spices thoroughly into the fat and leave the duck breast at room temperature for half an hour.
Choose a frying pan. Cast iron is best for this recipe.
Place the duck breast on the cold pan, fat side down. Set the plate heat to half heat. Soon the fat will start to melt, so no extra oil is needed for frying. Cut a sprig of rosemary into the fat to add flavour.
Fry until the fat side of the fillet has shrunk to a thin crisp (5-10min). Do not burn the duck.
Pour off the excess fat and turn the fillet over. Insert a thermometer into the thickest part and bake until the internal temperature reaches 54C. If you do not use a thermometer, leave to fry for about 3 minutes. The result should be a rosee coloured, juicy meat inside the fillet.
Wrap the meat in foil to rest for 10 minutes. Slice the duck and serve with cranberries and rosemary.