Argentinian-style Grilled Flank Steak

In the bowl of a food processor, combine parsley, thyme, oregano, basil, garlic, cilantro, onion, pistachios, olive oil, lemon juice and vinegar. Pulse until just blended. Season with salt and pepper, stir to blend.

Reserve 1 cup of the sauce from the food processor and place the remaining sauce in a non-reactive bowl, cover and chill in the refrigerator.

Rinse beef under cold running water and pat completely dry with paper towels. Season beef with salt and pepper and place in a resealable plastic bag. Add the reserved chimichurri sauce and seal the bag. Refrigerate to marinate for at least 4 hours or overnight, turning once or twice.

Remove beef and sauce from refrigerator 30 minutes prior to grilling.

Preheat a gas or charcoal grill to high heat. Remove the steak from the marinade and pat dry with paper towels. Place the steak on the grill and cook to desired doneness, about 6 to 8 minutes per side for rare to medium-rare Transfer the steak to a cutting board and let stand for 5 minutes before carving.