Place steaks in a large baking dish and pour 1/2 of the chimichurri marinade over the steaks. Turn to coat the steaks. Cover and marinate in the refrigerator for 2 hours.
Preheat grill to high. Remove steaks from the refrigerator 20 minutes before grilling. Remove steak from marinade and season with salt and pepper. Grill for 4 to 5 minutes on one side until golden brown, turn over and continue grilling for 4 to 5 minutes for medium-rare doneness.
Remove from grill, let rest 10 minutes and serve with remaining chimichurri on the side.
Combine all ingredients in a bowl and season with salt and pepper. Divide the chimichurri between 2 bowls. Use on 1/2 as a marinade and 1/2 as the finishing sauce.