In a bowl combine olive oil, Worcestershire sauce, vinegar, salt, pepper, cumin, paprika, garlic and onion powder and give it a stir. Pour marinade in a large zip lock bag. Add steak, get most of the air out and close tight. Marinate for at least 15 minutes (no need to refrigerate) or up to 6 hours (refrigerated).
Prepare the chimichurri sauce - place all ingredients in a jar, close and shake well or stir in a small bowl.
Preheat gas grill to medium high heat. (400 F)
Clean grill grates.
Grill for approximately 3-6 minutes per side for medium.
Place on a platter or cutting board and let steak rest for 5-10 minutes.