Combine first 6 ingredients in a shallow dish. Add steak to dish; cover. Marinate in refrigerator for 1 hour; turning after 30 minutes.
Preheat grill to medium-high heat. Remove steak from marinade and discard marinade. Thread steak onto 8 skewers; sprinkle with salt. Place skewers on grill rack coated with cooking spray. Grill 2 minutes on each side or until desired degree of doneness. Grill tortillas 30 seconds on each side or until lightly charred; keep warm. Place 2 tortillas on each of 4 plates and divide steak evenly among tortillas. Divide the Quick Pickled Cabbage evenly among tacos; sprinkle with onions.
To make the quick pickled cabbage: Place 3 cups chopped Napa cabbage in a medium bowl with 2 crushed garlic cloves. Bring rice vinegar, soy sauce, sugar and chile paste to a boil. Pour hot vinegar mixture over cabbage; toss. Let stand at least 30 minutes.