Cleaning and washing vegetables. Cut Chinese cabbage into bite-sized pieces, celery and cucumber into thin slices. Peel carrots, if necessary notch them all around with a knife and cut them into slices.
Peel onion and ginger and cut into fine rings or very thin strips. Mix everything. Mix rice vinegar, sake, mirin, soy sauce and 50 ml water and pour over the vegetables. Cover with a flat plate and weigh down with a tin.
Let everything marinate for at least 12 hours.