Cut pork in half crosswise, then butterfly each piece and pound them between pieces of plastic wrap until they are 1/4- to 1/2-inch thick.

Mix flour with salt and pepper in a wide, shallow dish.

Dredge pork thoroughly in seasoned flour, shaking off any excess.

Mash tomatoes and goat cheese together in a small bowl.

Place the floured tenderloin pieces on a flat surface.

Spread half of the goat cheese mixture over each piece, then arrange half of the arugula leaves on each piece.

Roll up each piece of pork, beginning with the narrowest point, so that it will be inside and the final edge of the roll will be relatively straight. If at all sticky, roll in flour again.

Preheat the oven to 400°F.

Heat oil in large cast-iron skillet over medium high heat and brown pork on all sides, turning carefully so as not to unwrap the rolls.

Start and end with the open side down to seal it shut, using a few toothpicks to seal it, if needed.

Transfer skillet to oven and cook 20 to 25 minutes, until completely cooked through.

Transfer pork to a large platter and set aside to let rest for 5 minutes. Carefully cut tenderloin into 3/4-inch thick slices with a very sharp knife.