In a bowl, mix 3 tbsp of teriyaki sauce, the beef, garlic and ginger. Cover and leave to marinade in the fridge for 1-4 hours.
Coat a wok or frying pan with oil and place over a high heat. Add the beef mixture, cook for 3-4 minutes. Add the mushrooms, carrots, peppers and broccoli. Cook for a further 4-5 minutes.
Stir in the noodles, mangetout and 2 tbsp. of teriyaki sauce. Cook for 3 minutes and serve.