Process first 7 ingredients in a food processor or blender until blended, and rub cilantro mixture over sirloin steak. Chill 2 hours.
Grill, covered with grill lid, over medium-high heat (350° to 400°) 10 to 12 minutes on each side or to desired degree of doneness. Let stand 10 minutes.
Cut steak diagonally across the grain into thin strips. Serve with Zesty Corn Salsa; garnish, if desired.