Add the beef strips to a plate and sprinkle over the Chinese five spice powder. Toss to coat.
Spray a large frying pan or wok with low-calorie cooking spray and set on a medium heat. Add the beef strips and fry for 4 -5 minutes until browned on all sides. Transfer the beef strips to a plate and leave to one side.
Add the red pepper, green pepper, chilli and garlic to the pan and fry for 2 minutes.
Combine the soy sauce, rice vinegar, sweetener, ginger and chilli powder in a small bowl, pour into the pan and stir to coat the vegetables for 1 minute.
Add the beef strips back to the pan and cook for a minute until heated through.
Sprinkle with sliced spring onion and serve with basmati rice or your choice of accompaniment.