Combine all the ingredients for the steak rub. Rub well into the steak, place in a large plastic zip bag and marinate in the refrigerator for a couple of hours or preferably overnight.
To make the sauce, combine the vinegar, garlic, jalapeños, and bay leaf in a food processor or blender and process until smooth. Add the onion, parsley, oregano, salt and pepper and pulse until blended but not pureed. Whisk in the oil and allow to sit for a couple hours to blend the flavors.
Before grilling, remove the meat from the refrigerator and bring to room temperature.
Grill the steak over a medium hot fire for about 20 minutes, turning often for medium-rare (150 degrees F. internal temperature). Remove the steak from the grill, allow to sit for 5 minutes, then slice the meat against the grain and arrange on a serving platter. Ladle some of the chimichurri sauce over the meat and serve the remainder on the side.
