Pat steak dry with a paper towel and then sprinkle with salt and pepper; let stand on a rack set over a baking sheet.
Bring a large cast-iron skillet to high heat until very hot, 6 to 8 minutes. Add oil and swirl pan until the oil shimmers. Place steak in centre and flip every 30 to 40 seconds, rotating the cooking spot in skillet, until a golden-brown crust develops, about 4 minutes.
Reduce heat to medium-high. Add butter and garlic and continue to cook steak, flipping and basting the foaming butter with a large metal spoon to evenly brown any light spots. Baste butter over steak, tilting pan to scoop and spoon over steak, until a digital thermometer inserted in centre reads 130°F for medium-rare, about 8 minutes, or until desired doneness.
Transfer steak to rack and let rest 5 minutes before slicing across the grain. Serve with juices and truffle butter.