Kombu-jime 昆布〆is a technique used for briefly curing fish or for making a quick pickle from root vegetables. It involves sandwiching the fish or vegetables between two slices of kombu and refrigerating.
Here is a translation of this video, which is described here using hamachi (yellowtail/amberjack) but which can be applied to any kind of fish and in fact you could use it for root vegetables as well for a quick pickle.
Cut the fish into slices between 5 – 6 mm thick
Sprinkle with salt
Slice the daikon using the technique known as katsuramuki and then finely slice julienne
Place the sliced daikon in water to make it stay crisp. Drain.
Cut the wakame into bite-size pieces
Wipe the kombu with a damp cloth
Brush the kombu with sake
Place the fish one by one along the surface of the first piece of kombu
Place the second piece of kombu on top
To prevent exposure to the air, wrap the kombu sandwich tightly in plastic wrap
Place the wrapped kombu in the refrigerator for about an hour and a half
Mix a little shoyu with dashi
Arrange the sliced daikon, wakame, fish slices on a plate and add a little benitade (water pepper) and wasabi. Serve with the shoyu-dashi dip.