Preheat the oven to 500°F. Blot the steaks dry with paper towels. Keeping their surface dry will help create a good crust.
Season the steaks on both sides and the fatty edge with kosher salt and black pepper.
Heat a well-seasoned cast-iron skillet over high heat until it's smoking. If the skillet is well-seasoned, there's no need to add any oil.
Add the steaks to the skillet. Cook them for 2 minutes per side plus 30 seconds on the edges. You can lower the heat to medium-high if the skillet gets overheated, but generally speaking, you want it super-hot.
Very carefully, using oven mitts, transfer the hot skillet to the preheated oven. Leave it there for about 3 minutes for medium-rare steaks or 5 minutes for medium-done steaks.
Transfer the steaks to a warm plate and loosely cover them with foil to keep them warm. Let them rest for 5 minutes, then top them with butter and serve.
Video
Notes
You could remove the steaks from the fridge an hour before cooking them to bring them to room temperature. But since I like my steaks medium-rare, I prefer them to be refrigerator-cold. This enables me to give them a good sear while keeping their inside red and warm. There's less of a risk of overcooking them this way.
If you like your steaks rare or if they are thinner - around 1 inch thick - you can skip the oven and simply pan-fry them for 3 minutes per side plus 30-60 seconds on the edges.
The nutrition information is approximate and was taken from the USDA database. To lower the sodium content to around 740 milligrams per serving, use just one teaspoon of Diamond Crystal Kosher Salt or ½ teaspoon of any other salt.
Leftovers: Reheated steak isn't very good. So while the leftovers can be kept in the fridge, in an airtight container, for up to 4 days, it's best to only cook as much as you can finish immediately. If you end up with leftovers, try them cold - they're surprisingly good (like thick, fatty slices of cold roast beef). If you must reheat them, do so gently in the microwave, covered, at 50% power.