Dry-Brine the Steak

1. Pat the steak completely dry with paper towels, then season both sides with salt equal to about 1% of the steak’s weight. For a 16 oz (454 g) steak, use about 0.16 oz (4.5 g) of salt, or roughly:
   1 1/2 teaspoons Diamond Crystal kosher salt,
   1 teaspoon Morton kosher salt,
   or 3/4 teaspoon table salt.
2. Place the steak on a wire rack over a baking sheet and refrigerate uncovered for at least 1 hour, preferably 2 to 4 hours for deeper flavor and a better crust.
3. If you have less than 1 hour, skip the dry brine and season the steak right before searing, or add salt to the sliced steak after cooking.

Boil the Potatoes

1. If the steak was dry-brined, take it out of the fridge at least 30 minutes before cooking and let it rest at room temperature.
2. Peel the potatoes and cut them into even quarters. Add them to a pot, cover with cold water, and add about 1 teaspoon of salt. Cover and bring to a boil over high heat. Remove the lid, reduce the heat to medium, and cook until fork-tender, about 15 to 20 minutes.
3. While the potatoes cook, peel the garlic for the garlic herb butter sauce and, if using fresh herbs, chop them. Set everything aside until it’s time to make the sauce.
4. Once the potatoes are tender, drain them well in a colander and return them to the pot. No colander? Use the lid to hold the potatoes back and carefully pour off the water.

Mash the Potatoes

1. Set the pot of potatoes over low heat for 1 to 2 minutes, gently shaking it once or twice, to cook off any excess moisture. Turn off the heat.
2. Cut the butter into small cubes, then add it to the pot along with the milk. Let the butter melt and the milk warm up for about 1 minute, then mash just until smooth. Add more milk as needed.
3. Cover the pot and set it aside to keep the mashed potatoes warm. Preheating the pan and searing the steak takes about 15 to 20 minutes, so they’ll stay warm until you’re ready to serve.

Cook the Steak

1. Turn on the exhaust fan or open a window.
2. Heat a heavy skillet over medium-high heat for about 3 minutes. Add 2 tablespoons of high-smoke-point oil and heat for another minute. While the skillet heats, pat the steak dry with paper towels.
3. If the steak has a fat cap, like a strip steak or picanha, hold it fat side down with tongs and sear for 60 to 90 seconds, until the fat is browned and crisp.
4. Lay the steak flat in the skillet and sear, flipping every 30 seconds. After about 3 minutes, start checking the internal temperature. Insert a meat thermometer horizontally into the thickest part of the steak. Remove the steak from the pan when it reaches the pull temperature for your preferred doneness:
   105°F (41°C) for rare,
   115°F (46°C) for medium-rare,
   125°F (52°C) for medium,
   135°F (57°C) for medium-well,
   145°F (63°C) for well-done.
   See the complete steak temperature chart below.
5. Transfer the steak to a plate and rest for 5 minutes. While the steak rests, make the garlic herb butter sauce.

Make the Garlic Herb Butter Sauce

1. Add 5 to 6 tablespoons (75 to 85 g) of butter to a small saucepan and melt over medium heat. Stir in the thyme or rosemary and cook for about 1 minute.
2. Press the peeled garlic through a garlic press, or finely chop it with a knife. Add the garlic and cook for 30 to 60 seconds, stirring, until you can clearly smell the garlic but it has not started to brown. Turn off the heat.
3. Keep the heat low enough to prevent the butter from burning and the garlic from browning.

Serve the Steak with Mashed Potatoes

1. Season the mashed potatoes with salt and pepper to taste and stir well. Spoon them onto plates, then slice the steak and arrange it over the potatoes. Pour the garlic herb butter sauce over the top and serve immediately while everything is hot.

Steak Temperature Chart