¾ cup olive oil
¼ cup red wine vinegar
2 TB freshly squeezed lemon juice
¾ cup chopped flat-leaf parsley
¼ cup chopped fresh leafy herbs of choice: basil, cilantro and/or mint (optional)
3 TB fresh oregano, rough chopped (or 3 tsp dried)
3 TB chopped garlic
3 TB chopped shallots
2 tsp kosher salt, plus more for seasoning
¾ tsp freshly ground pepper, plus more for seasoning
2 pounds skirt steak
Place all of the ingredients (except the steak!) in a bowl of a food processor or a blender. Pulse until well combined, but do not puree. The sauce should be course and assertive in flavor. Taste and adjust seasonings to your preference. Remove a few spoonfuls of the sauce and set aside for serving when steak is done cooking.
Cut the skirt steak into smaller pieces, about 4 inches in length, making note to cut thinner pieces from thicker ones, as the thicker pieces may need more cooking time. Place the steak in a shallow bowl or dish and pour the remaining sauce over, making sure to coat the meat well. Cover with plastic and refrigerate for at least 2 hours and up to 4 hours.
30 minutes before you are ready to grill, take the steak out of the fridge and allow to come to room temperature. Brush the excess chimichurri sauce off the steak and season lightly with kosher salt and freshly ground pepper.
Pre-heat the grill to medium-high (between 400-450 degrees). When the grill is hot, cook the steak, about 3 minutes per side for medium rare. For more well done temperature, leave on the grill for an additional minute or two per side.
Place cooked steak on a cutting board or plate, cover loosely with foil, and let rest for 10 minutes before slicing thinly against the grain.
Serve with remaining sauce and a hearty slice of grilled bread to soak up the sauce and juices.