4 pound porterhouse steak
1 cup fresh flat-leaf parsley leaves
2 tablespoons fresh oregano leaves
1 shallot, chopped
4 cloves garlic, chopped
Kosher salt and freshly ground black pepper
1/2 teaspoon red chile flakes
1/4 cup red wine vinegar
1/4 cup extra-virgin olive oil, plus more for steak
1. About half an hour before grilling, bring steak to room temperature.
2. Pulse parsley, oregano, shallot, garlic, 2 teaspoons salt, and chile flakes in a small food processor until roughly chopped. Add vinegar, oil, and 1 tablespoon water and pulse to a textured sauce. Transfer sauce to a serving bowl.
3. Preheat grill to medium.
4. Brush steak with oil and season generously with salt and pepper. Grill steak until seared and lightly charred, turning once, about 11 minutes per side. Hold steak with tongs and sear edges. Cook until an instant-read thermometer, inserted into steak registers 125 degrees F for medium rare.
5. Transfer steak to a cutting board, cover loosely with foil, and rest for 10 minutes.
Slice steak and serve with chimichurri sauce.