½ cup extra-virgin olive oil
¼ cup red wine vinegar
2 tablespoons lemon juice
1 cup chopped flat-leaf parsley
4 tablespoons chopped fresh basil
1 tablespoon chopped fresh oregano
2 tablespoons minced garlic
2½ tablespoons minced shallot
1 teaspoon crushed red pepper
1½–2 pounds flank, skirt, or flap steak
To make the sauce, combine in the bowl of a food processor the olive oil, vinegar, lemon juice, parsley, basil, oregano, garlic, and shallots. Pulse until well blended, but without pureeing. Add ½ teaspoon salt, ¼ teaspoon pepper, and the crushed red pepper. Set aside 1 cup sauce and cover with plastic wrap; reserve at room temperature for up to 6 hours.
Season the steak with 1 teaspoon salt and ¼ teaspoon pepper per side and place in a large resealable plastic bag. Add the remaining chimichurri sauce. Seal bag and refrigerate the steak for at least 2 hours.
Preheat a grill to medium heat or heat a cast-iron skillet or grill pan to medium.
Remove the steak from the refrigerator and let it come to room temperature for 30 minutes. Brush the excess chimichurri sauce off the steak and set the steak over the hot grill. Cook 2 to 3 minutes per side, or until desired doneness.
Allow the steak to rest for 5 to 7 minutes before slicing across the grain into 2-inch-wide strips.
Serve with reserved chimichurri sauce and a side of cruciferous vegetables or cauliflower mash and side salad.
MAKES 4 TO 6 SERVINGS