Place the flank steak in a shallow pan and pour in the soy sauce.
Cover the pan with aluminum foil and let the steak marinate at room temperature for one hour.
Flip the steak over and continue to marinate for one more hour at room temperature.
Remove the steak from the soy sauce and pat dry with paper towels.
Set your air fryer to 425F for 10 minutes.
Place the steak in the air fryer and cook for five minutes.
Flip the steak over and cook for another five minutes.
Check the internal temperature of the steak and either remove from the air fryer or cook a few more minutes to desired temperature. I prefer an internal temperature of 130F.
Cover the cooked steak with foil and let rest for 15 minutes while you prepare the Cauliflower Stir Fry according to package directions.
Slice the steak thinly, across the grain, and serve with the cauliflower rice stir fry.
Add teriyaki sauce or sriracha chili garlic sauce if desired.