COMBINE all ingredients for the sauce in a bowl. Set aside.
USING a large bowl, add salt, pepper, and tapioca starch together and add the chicken so that all pieces are well coated.
PREHEAT the air fryer to 375°F, and spray the tray or basket with avocado or olive oil. Add the chicken in a single layer (making sure the pieces do not touch each other) and air fry for 10-12 minutes, flipping halfway through until golden and crispy. You will most likely need to do this in two batches. Don’t be afraid to spray more oil onto the pieces!
HEAT a large cast iron pan (or saucepan) over medium-high heat and add avocado oil while the chicken is cooking.
COOK the onions, mushrooms, and celery for about 5-7 minutes until soft—season with salt and pepper.
ADD the air fryer chicken to your cast iron and mix with the cooked vegetables.
POUR in the prepared sauce and let it come to a boil. Simmer for 1-2 minutes until the sauce is thickened. Then turn off the heat.
SERVE over cauliflower rice and add the scallions, cilantro, sesame seeds, and red pepper flakes (if you like a little heat!) on top.