Let the steak rest out of the fridge at room temperature for at least 20 minutes. Preheat a cast iron skillet to medium-high with the olive oil. Sprinkle the steak with the salt on both sides.
When the skillet is hot, add the butter to the pan and swirl it to melt. When the butter foams and browns slightly, add the steak to the skillet. Don't touch it or move it for 5 minutes. After 5 minutes, flip the steak (it should have a nice dark crust, let it cook for another minute or two and increase the heat if needed) and let it cook without disturbing for 3 minutes more.
Remove the steak to a plate to rest for at least 10 minutes. Reduce the skillet heat to low, and add the shallots to the pan. Stir the shallots for a few minutes to soften and turn brown, then remove the skillet from the heat while you slice the steak.
When the shallots are done and the steak has rested, thinly slice the steak against the grain and remove any large pieces of fat.
Top the steak with spoonfuls of the shallots, and serve with your favorite side dishes. Enjoy!
This recipe was originally posted at http://funnyloveblog.com/2017/09/26/pan-seared-strip-steak/