1) Chop the fish until it turns into fine paste.
2) In a bowl, combine soy sauce, vinegar, sugar and ginger.
3) Stir in the fish and let it stand for 1 hour.
4) Cut it lengthwise, scoop out the seeds and slice very thin.
5) Pour the fish mixture over them and let it stand 10 minutes.
6) Serve in a bowl with crackers, as a dip.