In a small bowl, whisk together chicken broth, oyster sauce, sugar, cornstarch and vinegar. Set aside.
In a wok or large skillet, heat half of the oil over medium-high heat. Stir-fry chicken, salt and pepper until chicken is cooked through. Transfer to plate and keep warm.
Add remaining oil to wok, stir-fry peppers, onions and chili paste until vegetables begin to soften. Return chicken to pan.
Add cornstarch mixture, stir-fry for 1 minute. Add cashews and green onions, stir-fry for 1 minute. Serve over rice or noodles.