Add the chicken and stir-fry for 5-6 minutes, or until brown. Transfer to plate and set aside.
Return the pan back to medium heat and add more oil as needed. Toss in the zucchini, bell peppers and dried chili peppers (if using) and cook for 2-3 minutes, or until the vegetables are crisp-tender and the chicken is cooked through. Pour in the remaining sauce and add the cashews. Toss everything together and allow sauce to bubble and thicken. Season with salt, pepper or additional red pepper chili flakes as needed.
Remove from heat and serve warm on a large platter or over zoodles, cauliflower rice( paleo), quinoa or regular rice or noodles. Sprinkle with sesame seeds and green onions if desired.