Prepare the Steak

1. Pat the porterhouse steak dry on both sides with paper towels.
2. Season it with salt equal to about 1% of the steak’s total weight. For a 21 oz (600 g) steak, use about 0.21 oz (6 g), or roughly:
   2 teaspoons Diamond Crystal kosher salt,
   1 1/3 teaspoons Morton kosher salt,
   1 teaspoon table salt.

Dry-Brine the Steak

1. Place the salted porterhouse steak on a wire rack set over a baking sheet and refrigerate uncovered for 4 to 6 hours for best results. One hour is the minimum.
2. If you have less than an hour, do not salt it ahead of time. Season it right before it goes into the skillet, or cook the steak unsalted, then season to taste with a small amount of finishing salt after slicing

Make the Garlic-Herb Compound Butter

1. Cut the butter into small cubes and place in a bowl.
2. Let it sit at room temperature until soft enough to mix but not melted. To soften it faster, microwave in 5-second bursts, checking after each one to make sure it doesn’t melt.
3. Add the salt, black pepper, rosemary, parsley, and garlic. Mash and mix with a fork until well combined. Taste and adjust seasoning as needed. Cover the bowl and refrigerate until ready to use.

Preheat the Pan

1. If you dry-brined the steak, take it out of the fridge about 15 minutes before cooking. Take the compound butter out at the same time so it can soften slightly.
2. Turn on the exhaust fan or open a window because searing gets smoky.
3. Heat the pan over medium-high heat for 3-4 minutes. Then add 2 tablespoons of high-smoke-point oil and heat for about 1 minute.
4. While the pan heats, pat the porterhouse dry again with paper towels. Once the oil starts to smoke, the skillet is hot enough to sear the steak.

Pan-Sear the Porterhouse Steak

1. Carefully place the seasoned porterhouse in the hot skillet. If using a gas stove, position the strip side closer to the edge of the pan and the filet closer to the center for more even cooking.
2. Gently press the steak against the pan for good contact.
3. Cook, flipping every 30 seconds. Check the temperature of both the strip and filet as you go, and continue until each 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.
4. If one gets there first, angle the steak so only the cut that needs more time stays in contact with the pan while keeping the finished side away from the heat. Cook for another 30 seconds, checking the temperature as needed.
5. Start checking the temperature after about 3-4 minutes of cooking. Insert the thermometer horizontally from the side into the center of each muscle, keeping the probe away from the bone.
6. Once both cuts are at the right temperature, remove the steak from the skillet, top with 1 to 2 tablespoons of compound butter, and let it rest for 5 minutes before serving.

Slice and Serve

1. Once the steak has rested, cut the strip and filet from the bone.
2. Slice thinly and serve with your favorite sides.

Temperature Chart