Remove steak from fridge. Season one side of steak by rubbing truffle salt into steak. Season other side by rubbing salt, pepper, and the balsamic vinegar into steak. Let stand 15 minutes.

Heat butter on medium high heat in a heavy cast iron skillet until bubbling, almost browning. Place steak into pan, balsamic side down, cooking 6 minutes per side for a medium rare steak. Press steak in the middle to judge desired doneness. Remove steak from heat, let stand for 10 minutes before serving.