Heat the oil in a frying pan over a medium-high heat. Season the pork medallions on both sides with salt and freshly ground black pepper and fry for 3-4 minutes on each side, or until beginning to turn golden-brown.
Add the sultanas, cider, mustard and cream and simmer until reduced and thickened. Season, to taste, with salt and freshly ground black pepper.
To serve, place the pork into a serving dish and sprinkle over the chives.