Heat a wok or skillet over medium heat. Add oil and swirl to coat.
When the oil is hot (but not burning), add dried chilies and stir-fry for 1 minute until they darken. Use a slotted spoon to remove chilies, and set aside.
Increase heat to medium high, and add chicken. Stir-fry until chicken is cooked through, about 2 minutes. (The chicken will turn white and if using a probe thermometer, temperature will reach about 165° Fahrenheit).
Add vegetables and stir fry until onions in the mix start to wilt, about 5 to 10 minutes depending on if using frozen or thawed.
Add fish sauce, soy sauce, and sugar and stir fry for another minute or two.
Add cashews and reserved chilies and stir well.
Serve over sticky rice.