The taste is all in the prep.
Slice topside of beef thinly and leave in teriyaki marinade for 2-3 hours in the fridge, or overnight. (Teriyaki is made from 50ml Mirin and 50ml Soy Sauce).
Place noodles in a bowl and tip over boiling water. When soft, drain off and reserve.
Stir-fry noodles in wok or large frying pan with oil and butter. Add garlic, ginger, spring onions and a little soy sauce to moisten. Arrange noodles on plate.