Ingredients
1 c. balsamic vinegar
1/2 c. extra-virgin olive oil
2 tbsp. extra-virgin olive oil
1/4 c. finely chopped rosemary
3 lb. porterhouse steak
2 tsp. kosher salt
2 tsp. coarsely ground pepper
Preparation
Step 1In a sturdy resealable plastic bag, combine vinegar with 1/2 cup olive oil and rosemary. Add steak, seal bag, and refrigerate overnight, turning bag several times.Step 2Preheat oven to 425 degrees F and bring steak to room temperature. Heat a grill pan. Remove steak from marinade and season with salt and pepper. Rub side with remaining 2 tablespoons olive oil. Grill over moderately high heat until nicely charred on top and bottom, about 5 minutes per side. Transfer steak to a rimmed baking sheet and roast about 30 minutes, until an instant-read thermometer inserted into tenderloin (smaller section) registers 125 degrees. Alternatively, build a fire on one side of a charcoal grill or light a gas grill. Grill steak over moderate heat, 5 minutes on each side. Transfer steak to cool side of grill, close lid, and cook 30 minutes longer. Transfer steak to a carving board and let rest 10 minutes. Slice steak across grain and serve immediately.
