1/2 cup balsamic vinegar
1/4 cup olive oil
1 Tablespoon finely chopped rosemary
One 3-pound fillet mignon or porterhouse steak, about 4 inches thick
2 teaspoons kosher salt
2 teaspoons coarsely ground pepper
HOW TO MAKE THIS RECIPE
In a sturdy resealable plastic bag, combine the vinegar with 1/4 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. 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 12- `5 minutes for rare or if your grill pan is oven proof just put it in the oven, Or…, 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.