Pickled ginger is traditionally served with sushi. You can buy it in specialized shops. You can also make it on your own, but you will need rice vinegar. You can also use normal vinegar, but your pickled ginger will have a slightly different taste. Buy young ginger, which does not contain so many fibers, peel it and cut into thin slices. Toss the slices for half a minute into boiling water, then pour the water away and let the slices cool. In the meantime, prepare a glass with rice vinegar, sugar and salt. Put the slices into this glass and leave it one day in a fridge. Your pickled ginger can be kept in a fridge for several weeks.