Cut the monkfish medallions like a butterfly steak, fill each with 1 slice of Parma ham and 2 sage leaves and pin tight with wooden sticks. Cover and put in a cool place, this can be prepared in the morning.
Heat the oil in a coated pan, season the filled monkfish medallions on both sides with salt and pepper and fry in the pan over high heat for a total of 5 minutes, turning once. Take out of the pan and keep warm. Froth the butter in the pan, add the remaining sage leaves and toss.
Serve the monkfish saltimbocca with the sage butter.