Konbushime (raw fish sandwiched between kelp) (昆布〆め)
Konbushime is a local dish in Toyama Prefecture.
It is also called kobujime or konbujime
It is made by sandwiching sashimi (fresh slices of raw fish) between pieces of konbu (kelp) and letting it stand overnight in the refrigerator, and is served with wasabi joyu (soy sauce mixed with wasabi paste).
Konbushime is one of the uses of konbu for people in Toyama who have consumed konbu in large quantity since the Edo period in which konbu was sent by kitamae-bune (cargo ships) from Hokkaido.
It is known that this method enables sashimi, which spoils rapidly, to keep its freshness for a couple of days.
The sashimi becomes firm with its fluid absorbed by the konbu, and gets a different depth to its original flavor with the konbu's flavor, including glutamic acid, transferred to the fish.
Konbushime is usually made with yellowtails and marlins, though it may also be applied to most sashimi including sea breams, squids and deep-water shrimps.
Even though konbushime pulls strings when flipped to eat, this does not mean it is rotten; this is caused by the mucin derived from the konbu. However, when it smells rotten, it may be so.
The konbu, being tender due to absorbed liquid from the sashimi, can also be eaten, as a matter of course.
In the Kansai region, raw flatfish is sandwiched between pieces of konbu for a few days to transfer its flavor to the fish, which is called konbushime as well.