Pat steaks dry and sprinkle both sides with rub. After rub is applied, let steaks sit on counter for the chill to leave the meat. Prepare grill for cooking steaks - will be grilled on high heat. Grill steaks on lightly oiled grill rack turning over once and moving around to avoid flare-ups if necessary. Cook time will be 6 to 8 minutes total for medium-rare, for steaks that are 1/4 inch thick. Transfer steaks to a cutting board and let stand, loosely covered with foil, 3 to 5 minutes. Thinly slice steaks diagonally. Plate and serve steak with chimichurri sauce.
In a large mixing bowl, combine all ingredients except oil. Add oil and blend with food processor until thoroughly mixed.
Place all ingredients in blender. Turn blender on low 15 seconds until fennel seed is broken down. Store in airtight container and use when needed.