Slice steak thinly, and place in a ziplock bag along with sliced pepper and onion.
Whisk together remaining ingredients for the marinade and pour into bag. Massage so that the steak and veggies are fully coated. Marinate up to 24 hrs. Try to marinate at least 1 hr. If possible
Heat cast iron pan on high. Add the contents of the bag and let cook without stirring for at least 3 minutes until veggies and steak begin to carmelize.
Continue cooking just long enough for steak to cook. Onions and peppers should still have a bit of crunch left.
Notes
serving size about 1 cup (8 oz) does not include cauliflower rice mixture