1. Season steak with salt and pepper and grill to your liking, about 5 minutes per side for medium rare.
2. While steak is resting after being grilled, make chimichurra sauce: add all ingredients except olive oil to food processor and process until parsley and garlic are well-chopped. Add olive oil in a steady stream through processor tube until the sauce is a nice thick consistency.
3. Slice steak against the grain, and garnish with sauce.