To prepare the marinade, grate the ginger and squeeze it well over a dish to yield 1tsp ginger juice.
Mix in the soy sauce and sake or wine. Place the pork slices in a shallow dish.
Pour over the marinade and turn them to coat well. Set aside for about 15mins.
Heat the oil in a frying pan. Place the pork in the pan, in a single rayer and add the marinade.
Fry over a medium-high heat, turning the pork once, until golden on both sides.
Arrange the pork on a plate. Pour cooking juices from the pan iver the pork and serve immediately.