Make the dressing. Mix the garlic and ginger with the soy sauce, sweet chilli sauce and sesame oil. Put the steaks in a non-metallic dish and add 2 tablespoons of the dressing, reserving the rest. Cover and leave to marinate for at least 2 hours, or preferably overnight.
Bring a saucepan of lightly salted water to the boil and cook the noodles for about 5 minutes or until done. Refresh in cold water, drain and transfer to a bowl.
Add the vegetables to the bowl with the noodles.
Heat a griddle pan on a high heat and cook the steaks for 5 minutes on each side until medium rare (longer if you prefer your meat well done). Allow to rest for 5 minutes and then finely slice. Drizzle the dressing over the noodle and vegetable mixture, add the sliced steak and combine well. Garnish with spring onions and toasted sesame seeds and serve immediately.