A cast-iron skillet is ideal for searing steaks because it distributes heat evenly and retains it well, which translates to deep, flavorful browning. In this recipe, we cook a porterhouse that’s large enough to serve four, then carve the meat off the bone for serving. Because the steak is very thick, it’s important for even cooking that it be at room temperature before it hits the skillet. This means taking the steak out of the refrigerator at least 30 minutes before you’re ready to cook it. The fat will smoke during cooking—it’s unavoidable—but you can turn down the burner a bit to reduce the smoking; it’s also a good idea to turn on the hood or open a window. A digital thermometer is the best way to test for doneness, however be sure to temp the center of the loin side—the larger, longer muscle on the steak—without touching the bone. A simple no-cook sauce allows the porterhouse to be the star of the meal. We offer two options below—one is a tangy, bright parsley sauce and the other an umami-rich, spicy-sweet sauce akin to the Korean condiment called ssamjang.