Peel, wash, dry the pork tenderloin and cut into medallions as thick as a finger. Finely chop the rosemary leaves and mix with the mustard.
Brush the medallions with the mustard, season with salt and pepper and coat each with a slice of San Daniele ham.
Heat a little olive oil in a pan, fry the medallions on both sides for approx. 2-3 minutes on both sides (depending on the thickness of the medallions).
Remove medallions from the pan, wrap in aluminum foil and keep warm in the oven.
If you insist on sauce, you can sweat 1/2 finely chopped onion and some tomato paste in the roasting set, pour red wine, broth or water on top, add a few green peppercorns and a little creme fraiche or cream if you want and make a quick sauce.