The first time my dad went to the Pacific Dining Car in Los Angeles was in the 1950s. His mother, my Nanny Lolo, loved it. She was fussy about steaks, and it was (and still is) one of the best steakhouses in LA. When I want steak at home, I think of the Pacific Dining Car's classic steaks, but with an updated way of cooking them: the reverse-sear method. The reverse-sear method was made famous by J. Kenji Lopez-Alt, as the way to get the perfect steak, every time. I usually hate techniques that feel like gimmicks--I like to cook things simply with as little fuss as possible. However, I tried it myself, and honestly...the hype is true. It takes more time, but it's easy and the best way to get a perfect steak. The key is to use a very thick slab of meat. If you use a thin steak, this process won't work--you'll cook it through too quickly.
To get an extra-crispy crust, place the steak on a wire rack set over a baking sheet and leave, uncovered, in the refrigerator overnight. The air in the refrigerator is dry and will help dry the outside of the steak.
When ready to cook, preheat the oven to 250 degrees F.
Generously season the steak all over on both sides with salt, pepper, garlic powder and mushroom powder if using.
Place the steak, still on the wire rack and baking sheet, directly into the oven. Cook, checking the internal temperature occasionally, for 20 to 40 minutes. Ideally you want the steak to be 120 degrees F for medium-rare/medium, which is my favorite.
Just before the steak comes out of the oven, heat a dry cast-iron skillet over high heat for 1 minute. Add the butter, then immediately add the steak to skillet and cook until each side is crusty and well browned, about 45 seconds per side, pushing down to sear. Using tongs, hold the steak sideways to sear the edges. Serve right away; there's no need to let reverse-seared steaks rest.