Mix the garlic, soy sauce, sugar, rice wine, spring onion and pepper with half the oil in a large bowl and ass thr steak. Mix well, cover and leave in the refrisgerator overnight.
Heat the reminaing oil in a large frying pan and when it's just beginning to smkoe, put in the beef cubes, in one layer. Cook, without stirring for about 1 minute - there shoudl be a thin crust at the bottom.
Shake the pan vigorously to loosen the beef (use tongs or chopsticks if you need to) and continue to cook, shaking the pan every so often, until the beef is cooked to your taste.