Ingredients
- 2 tablespoons rosemary, finely chopped, plus whole sprigs for serving
- Kosher salt and freshly ground black pepper
- 1 porterhouse steak (approximately 2 1/2 inches thick and 2 1/2 pounds)
- Extra-virgin olive oil, for drizzling
- 2 shallots
- 1 lemon
- 2 ounces anchovies packed in oil (8 to 10 pieces), drained (optional)
- Flaky salt, for serving
Directions
- One to 2 days before serving, mix together the dry rub and season the steak: Combine rosemary, 2 tablespoons kosher salt, and 1 teaspoon pepper in a small bowl and mix to combine. Pat the steak dry with paper towels (if needed). Season steak with the rosemary salt—including the bone and fatty edge—pressing it on if necessary. Drizzle a thin coating of olive oil on all sides and rub it into the dry rub. Place steak, bone-side down, into a gallon-size zip-top bag and place in the refrigerator so that it is standing up on the bone (do not seal the bag; you want air to circulate). Chill for 24 to 48 hours.
- When ready to cook, preheat oven to 300°F. Transfer steak to a rimmed baking sheet fitted with a cooling rack and place in oven. (If you have a probe thermometer, insert it into the thickest part of steak and set alarm for 125°F.) Cook undisturbed for 1 hour. Remove steak from oven and insert a digital thermometer into thickest part; it should register between 105°F and 115°F. Return steak to oven and cook 10 to 15 minutes more; check temperature again. It should register around 125°F. The temperature will rise very slowly at the beginning of the cooking, but will climb faster once the steak reaches around 110°F, which is why it’s important to check more frequently once you’re in that zone. The total cooking time should end up being between 65 and 75 minutes, depending on your steak and oven.
- Let steak rest at room temperature on cooling rack; the temperature will climb to about 130°F before dropping again. (You can hold the rested steak at room temperature for up to 2 hours, if desired).
- In the meantime, thinly slice the shallots and place in a small bowl. Cut the lemon in half and squeeze the juice from one half over the shallots. Season with salt and toss to combine; set aside. Cut the remaining lemon half into 4 wedges. Arrange the anchovies on a small plate, if using, and season with pepper.
- Preheat a large cast-iron skillet over medium-high for 3 to 5 minutes. Drizzle skillet with oil to coat, then add steak to pan and cook, pressing down occasionally to maintain contact with the surface, until very well browned on both sides, 8 to 10 minutes. Let rest, turning occasionally, for 10 to 15 minutes.
- To serve, carve steak off the bone, then cut against the grain into 1/2-inch-thick slices. Place steak bone on a large cutting board or platter and arrange slices on either side. Drizzle any accumulated juices from sheet pan over, then season with flaky salt and pepper. Serve steak garnished with rosemary sprigs, marinated shallots, anchovies, and lemon wedges for squeezing over.