Konbujime or kobujime is fresh fish or other seafood that is lightly salted and cured for a brief time in konbu seaweed, and served sliced like sashimi.
A popular drinking snack or side dish accompanying a traditional Japanese meal, the fish absorbs lots of umami and flavor from the konbu, taking on a rich, unctuous texture as the moisture is drawn out.
In addition, the method preserves the fish for a few days longer than if it’s left untreated, though it should not be used for long-term preservation. Konbujime is usually made with white fish, although the technique can be used to cure any fresh fish or seafood, and even meat.
Konbujime originates from Toyama Prefecture, where it was created in the Edo Period (1603-1868) when the area was part of the wealthy Kaga Domain. The region has long been known for the rich variety of seafood caught along its coastline, but never for its konbu, which grows best in cold waters. Currently, about 95 percent of Japanese konbu is produced in Hokkaido. (The word konbu may originate from the Ainu word “kompu,” although there are conflicting theories.)
The konbujime method came about by combining local seafood with konbu imported from Hokkaido on trading ships called kitamaebune, so called because the Sea of Japan coast of Honshu was known as Kitamae (“Northern Front”) by the people of Kyoto and Osaka. The ships’ main task was to carry goods from Hokkaido and northern Honshu along the Sea of Japan coastline in the Edo Period and early Meiji Era (1868-1912).
The powerful Maeda clan, who ruled the Kaga Domain, starting importing konbu from Hokkaido on kitamaebune in the mid-17th century. The konbu was then transported to Osaka, along with rice grown in the domain, for profit. Konbujime evolved concurrently to help preserve fish being exported inland, keeping it both fresh and safe to eat on arrival.
Konbujime eventually spread throughout the Kansai region, where it became especially popular in Imperial Kyoto, which had no direct access to the coast.
In this recipe, I’ve given instructions for making konbujime with oboro konbu as well as with regular konbu. Oboro konbu is the pale inner part of the konbu leaf that has been carefully shaved by hand into tissue-paper thin sheets.
Konbujime made with oboro konbu will have a more delicate flavor than that made with regular konbu, which has a more pronounced taste. The strength of the konbu flavor imparted is also dictated by how long the fish is left to cure.
Don’t confuse oboro konbu with tororo konbu. Although they look very similar, the latter has a slimy texture when wet since it is processed in a way to release the mucin in the konbu.
If used, this slime will transfer to the konbujime. It’s ultimately harmless, but the texture may not be quite what you were after.
Konbujime: Konbu seaweed-cured fish
Ingredients (makes several dishes):
• 200 grams sashimi-grade boneless white fish filet (see notes for suggestions)
• Sheets of oboro konbu, or large pieces (or whole leaves) of konbu
Salt the fish lightly on both sides.
If using oboro konbu, wrap 2-3 pieces or more around the fish several times like a parcel. Wrap the parcel in plastic wrap, and refrigerate for several hours, up to two days.
If using regular konbu, cut out two pieces that are about the same size as the piece of fish with kitchen scissors. Place the fish on one piece of konbu, then cover with the other piece of konbu. Wrap in plastic wrap and refrigerate for up to two days.
To serve, unwrap the plastic and konbu, and slice the fish about 7 millimeters thick, adding any garnishes you like. I’ve used steamed asparagus and fava beans, salted sliced cucumber, myōga ginger and baby shiso (perilla) leaves.
The longer the fish is cured, the more umami and konbu flavor it will have. It can be served as is, with a little vinegar sauce (such as ponzu or sanbaisu), or a squeeze of citrus like yuzu or sudachi.
Try it carpaccio-style, sliced very thinly and sprinkled with lemon juice and olive oil. You can also eat it like sashimi, dipped in soy sauce with grated wasabi or ginger.
Konbujime can be kept frozen in its konbu wrap for up to a month. Defrost in the refrigerator.
Make sure that the fish you are using is very fresh. Here I’ve used sakura-dai (red sea bream caught in the spring), but any white fish that is sashimi-ready can be used, such as hirame (flounder), shitabirame (sole) and sayori (halfbeak).
If you can get fresh, not frozen, shrimp, they can be used too. In Toyama Prefecture, konbujime made with fresh white shrimp is popular.
Make sure the fish you’re using is skinned, since it is impossible to remove the skin after curing it.