Heat 1 Tbsp oil in nonstick skillet; stir fry chicken until thawed, 5 minutes.
Add vegetables; stir-fry until crisp-tender. Stir in contents of sauce packet, cook until crisp tender. Stir in contents of sauce packet; cook until hot.
Microwave french fried onions 1 minute. Sprinkle over stir-fry. Serve warm.