Process first 8 ingredients in a blender or food processor until smooth, stopping to scrape down sides. Spread seasoning mixture evenly over steak; cover and chill 8 hours.
Grill steak, covered with grill lid, over medium-high heat (350° to 400°) 6 to 7 minutes on each side or to desired degree of doneness. Let stand 10 minutes; cut into thin slices.
Coat 1 bunch green onions and tomatoes evenly with cooking spray; sprinkle with salt.
Grill, covered with grill lid, over medium-high heat 10 to 15 minutes, turning occasionally. Coarsely chop vegetables. Serve with steak in warm tortillas.