Remove the steaks from the fridge and let them stand on the counter until they reach room temperature, about 30 minutes.
Place a cast iron or other heavy bottomed skillet over medium heat until very hot, 3 to 4 minutes. While the skillet is heating, pat the steaks dry thoroughly with paper towels. Season generously on both sides with fine sea salt and lightly with pepper.
Cook undisturbed until the bottom is nicely seared and releases easily from the pan, 3 to 4 minutes. Carefully flip and cook until the other side is seared and a meat thermometer stuck into the thickest part reads 120º to 125ºF for medium rare, 2 to 4 minutes longer.
Transfer the steak to a cutting board, tent with foil and let rest for at least 5 to 10 minutes (up to 20). Slice the steak against the grain and serve, sprinkling with flaky sea salt, if desired.