Thinly slice the steak against the grain and marinate in the marinade for a few hours or overnight.

Drain off the marinade and save it.

Coat the drained steak in cornstarch, shaking off excess.

Add the reserved marinade to the additional sauce ingredients.

Stir-fry the beef in oil in a wok and drain.

Stir-fry the onion in a tablespoon of oil,then add the cooked beef, scallion and cooking sauce.

Cook until thickened.

Fry the dried rice vermicelli (separate it into a single layer so it doesn't clump) in hot oil, it will puff up pretty much immediately; drain. Don't cook ahead, cook the stir-fry first.

Serve the stir-fry alongside or on top of the crisp noodles. Or serve with rice.