Heat the oil in a wok. Add the ginger and garlic, then stir-fry briefly until just coloured. Add the prawns and the whites of the spring onions, and cook for a further 3 mins. Pour in the beaten egg, let it set for a couple of secs, then break it up and stir well to scramble. Add the cooked rice and stir-fry everything together for 10 mins. Add the rest of the spring onions, rice wine and soy, then toss everything together well. Serve immediately.