1. Preheat the oven to 200C. Heat the oil in a large frying pan and brown the pork on all sides. Place in a baking dish and roast in the oven for 20-25 minutes, depending on the thickness of the meat.
2. While the pork is roasting, to the unwashed frying pan, add the sherry and stock and bring to the boil until reduced by about one quarter. Add the orange juice and rind and redcurrant jelly and simmer gently until dissolved. Taste for seasoning and add salt and pepper and finally the sage. The sauce should be thin and slightly syrupy.
3. When the pork is done, allow to rest for 10 minutes before slicing into medallions.
4. Serve with rice or new potatoes and stir-fried Savoy cabbage with apple juice.