Take off the outer zest of half an orange and half a lemon using a potato peeler. Next, with a sharp knife shred into really fine strips about 1/2 inch long.
Place the cranberry sauce, ginger and mustard powder in a saucepan, add the squeezed orange and lemon juice and place over a medium heat.
Now bring it up to simmering point, whisking well to combine everything together, then as soon as it begins to simmer turn the heat off.
Stir in the port and pour into a jug until needed.
When you are ready heat the oil in a medium sized heavy based frying pan, dry the steaks with kitchen paper then press peppercorns onto both sides of the steaks.
When the oil is smoking hot, drop the steaks into the pan and cook for 5 minutes on both sides for medium cooked steaks, 4 minutes for rare and 6 minutes for well done ones.
Halfway through add the shallots and move them about the pan until they cook and brown on the edges
30 seconds before the end of cooking time pour in the sauce, not over but around the steaks and season with salt.
Serve the steaks with the sauce poured over and garnish with watercress.
Another serving suggestion is to serve the steaks with mini jacket potatoes and green salad.