Remove steaks from refrigerator 30-45 minutes before grilling and pat both sides completely dry with paper towels. Trim excess fat if desired, leaving most of the fat cap intact for flavor.
Brush both sides of each steak lightly with oil, then season liberally with kosher salt and black pepper. Gently press seasonings into the meat and let rest while preheating the grill.
Clean grill grates thoroughly and preheat to high heat (450-500°F for gas, or until coals are white-hot for charcoal). Oil the grates using a paper towel dipped in oil and held with tongs.
Place steaks on the hottest part of the grill at a 45-degree angle to the grates. Close the lid and sear undisturbed for 4-5 minutes without moving or flipping.
Rotate steaks 90 degrees without flipping to create diamond grill marks. Continue cooking for another 2-3 minutes until the first side has a deep brown crust.
Flip steaks using tongs and position at a 45-degree angle again. Close lid and cook 4-5 minutes undisturbed, rotating 90 degrees after 4 minutes for diamond marks on the second side.
Insert an instant-read thermometer into the thickest part of the steak. Remove at 120-125°F for rare, 130-135°F for medium-rare, 135-145°F for medium, or 145-155°F for medium-well.
Optional: Place a cast iron skillet on the grill with butter, smashed garlic, and fresh herbs. Once butter foams, tilt skillet and spoon the mixture repeatedly over steaks for 1-2 minutes.
Transfer steaks to a clean cutting board and tent loosely with aluminum foil. Let rest for 5-10 minutes to allow juices to redistribute throughout the meat.
Slice steaks against the grain into 1/2-inch thick slices. Arrange on a platter, drizzle with accumulated juices, and top with a pat of butter if desired. Serve immediately.