Place chicken on a cutting board and cover with a piece of saran wrap. Pound chicken until it is uniform 1/4 inch thick (this helps tenderize the meat and really makes for a better stir fry!). Cut chicken into 1 inch cubes. Season chicken with salt, pepper and arrowroot flour.
Heat a skillet over medium-high heat with avocado oil. Swirl the pan so that the oil coats the bottom of the skillet evenly. When the oil is hot but not smoking, add chicken to skillet in a even layer (you may need to do this in 2 batches depending on the size of your skillet). Cook chicken until a golden brown crust has formed on each side, about 3 minutes per side.
Once the chicken has browned, add the toasted sesame oil and gently toss to combine. Add the green onions, the kimchi (some of the juices are ok too) and coconut aminos to the skillet. Bring to a simmer and cook, tossing occasionally, until the sauce has thickened, 2 to 3 more minutes.
Serve with cauliflower rice (if desired) and sprinkle with toasted sesame seeds. Enjoy!