Twice Cooked Pork Tenderlion

boneless pork tenderloin, about 1 pound
Salt and freshly ground black pepper
4 tablespoons butter, extra virgin olive oil, or a combination
1/4 cup cream
1 tablespoon Dijon mustard, lemon juice or Calvados, optional
Chopped fresh parsley leaves for garnish, optional

Sprinkle meat with salt and pepper. Put a large skillet over medium-high heat; a minute later add 2 tablespoons butter and/or oil. When butter foam subsides or oil dimples, add meat (curve it into skillet if necessary). Brown it well on all sides, for a total of 4 to 6 minutes. Turn off heat, remove meat from pan, and let it sit on a board. When skillet has cooled a bit, proceed.

Cut meat into inch-thick slices. Once again turn heat to medium-high, add remaining butter and/or oil and, when it's hot, add pork slices to pan. Brown on each side, about 2 or 3 minutes each. Turn heat to low and remove meat to a warm platter.

Add 1/2 cup water to pan, turn heat to high, and cook, stirring and scraping, for a minute. Lower heat slightly, add cream and cook until slightly thickened. Stir in mustard, lemon juice or Calvados, if you're using them, then taste and adjust seasoning. Serve meat with sauce spooned on top, garnished, if you like, with parsley.