In a large pan or wok, heat the oil on medium heat.
Add the chicken, in batches if needed (don't overcrowd the pan), to brown on each side, about 5-7 minutes total.
Remove chicken and set aside. Add vegetables to the pan and more oil if needed, and sauté until tender.
Whisk together all of the sauce ingredients in a small bowl.
When vegetables are done cooking, add chicken back, turn heat to medium-low and add the sauce. Add the cashews. Allow to thicken for 3-5 minutes.
Top with green onion and serve over steamed white rice, brown rice or cauliflower rice!