Combine soy sauce and cornstarch. Use a whisk, mix until the cornstarch is completely dissolved.
Add the rest of the ingredients to the soy sauce and cornstarch mixture. Mix until well incorporated. Set aside.
FOR THE STIR FRY
Heat a pan with oil. Add the chicken to brown and cook thoroughly. Push the chicken on one side of the pan, then add onion, garlic, and ginger, saute for a minute or until the onion is tender.
Add the rest of the vegetables, stir fry and cook until tender. Season with salt and red chili pepper flakes then stir to combine.
Add the sauce, cashews, stir until well mixed. Add green onions. Serve warm with steamed rice.
Notes
I don't overcook the vegetables, I'd like them crunchy.