The original recipe calls for layered, salted sliced salmon and daikon, pickled in a wooden barrel for a long time. This modern version is less salty and far easier to make.
Slice the daikon very thinly into rounds. Put in a shallow container, sprinkle with salt and vinegar, and add the snipped dashi-konbu. Mix and rub gently with the hands. Cover and leave in the refrigerator for 1 hour.