Preheat the oven to 350 degrees F/175 degrees C.
Rub the oil in a roasting pan. Sprinkle the pork with salt and pepper and rub the pork all over with the mustard. Set it in the pan and pour in 1/2 cup/125 ml water. Roast
until the pork is tender, about 1 hour 30 minutes. (If the water evaporates in the pan, add a little more.)
Remove the pork to a serving dish and keep warm. Fry
the shallot in the roasting pan on the stovetop. Deglaze
with wine and boil to reduce by half. Stir in the creme fraiche and rosemary
, and reduce to sauce consistency. Check the seasonings. Slice the pork, pour the sauce
on top and serve.