Buttery Steak and Potatoes

Preparation

1. Step 1

   Scrub and halve the potatoes and add to a medium pot. Cover with water and season very generously with salt. Bring to a boil over high heat, then reduce to a simmer and cook until tender, about 15 minutes. Reserve ½ cup of the cooking liquid, then drain the potatoes.

2. Step 2

   Meanwhile, heat a heavy skillet, preferably cast-iron, over medium heat until you see wisps of smoke. (Use one that’s large enough to lay the steak flat and leave room for basting, but has no more than 2 inches between the pan’s edge and the steak’s edge. Do not use a nonstick skillet.)

3. Step 3

   While the pan is heating, pat the steak dry with paper towels and season all sides very generously with salt, including the fat cap and edges. (Much of the seasoning falls off during cooking, so don’t be skimpy at this stage.) Hold the steak upright and give it a gentle tap along the cutting board to knock off any excess salt.

4. Step 4

   Add the oil to the heated pan, followed by the steak. (For a thinner steak, cook on medium-high heat. For a thicker steak, cook on medium heat.) Use a spatula to firmly press the steak into the pan to maximize contact and browning. Cook, undisturbed, for 1½ minutes, then flip, press firmly and continue cooking on the other side. After 1½ minutes, flip and repeat. Continue cooking the steak, flipping it every 1½ minutes, until the internal temperature reads 25 degrees less than your target temperature (see Tip) on an instant-read thermometer, about 10 to 20 minutes, depending on the thickness of the steak and the extent of its marbling.

5. Step 5

   Transfer the steak to a cutting board, pour out and discard the fat from the pan and wipe it out. Return the pan to low heat and add the butter, thyme and garlic. Once the butter has melted, return the steak to the pan and increase the heat to medium-low. Baste the steak with the butter, flip after 1½ minutes, and continue basting. Baste and flip the steak until 5 degrees away from your target internal temperature, 3 to 5 minutes. Remove steak to a cutting board to rest and season both sides generously with freshly ground black pepper.

6. Step 6

   Add potatoes to skillet, cut side down. Cook on medium-low heat until barely browned, about 2 minutes. Add ¼ cup of the reserved potato cooking liquid. Simmer until the sauce looks creamy and emulsified, adding more water if it looks greasy. Serve potatoes, garlic cloves, thyme and drippings with steak.