How can something so elegant and primal be fantatically delicious yet so quick and easy? I make this recipe when I want a feast for my family, or a crowd, during the winter months or for summertime grilling. Spotted in a Food & Wine magazine years ago by the wonderful Chef Nancy Silverton, the greatness is its simplicity: the steak; marinated in olive oil, rosemary and balsamic vinegar, holds onto these flavors while letting chemistry tenderize. It's a quick sear, then into the oven (or continued on a covered grill) for less than a half hour depending on the meat's weight. While the recipe - in its perfection - calls for porterhouse, I use it on any thick steak that can be called a roast. And the bone-in, while not essential, makes it that much better. Enjoy!
1 cup balsamic vinegar
1/2 cup plus 2 tablespoons extra-virgin olive oil
1/4 cup finely chopped rosemary
One 3-pound porterhouse steak, about 4 inches thick
2 teaspoons kosher salt
2 teaspoons coarsely ground pepper
In a sturdy resealable plastic bag, combine the vinegar with 1/2 cup of the olive oil and the rosemary. Add the steak, seal the bag and refrigerate overnight, turning the bag several times.
Preheat the oven to 425° and bring the steak to room temperature. Heat a grill pan. Remove the steak from the marinade and season with the salt and pepper. Rub the side with the remaining 2 tablespoons of olive oil. Grill over moderately high heat until nicely charred on the top and bottom, about 5 minutes per side. Transfer the steak to a rimmed baking sheet and roast for about 30 minutes, until an instant-read thermometer inserted into the tenderloin (the smaller section) registers 125°. Alternatively, build a fire on one side of a charcoal grill or light a gas grill. Grill the steak over moderate heat for 5 minutes on each side. Transfer the steak to the cool side of the grill, close the lid and cook for 30 minutes longer. Transfer the steak to a carving board and let rest for 10 minutes. Slice the steak across the grain and serve immediately.