The ABCs of Dashi
KOMBU― KELP ―昆布
Kombu (dried kelp) has a long history, just like katsuo-bushi (dried bonito). Kombu is mentioned in the Engishiki, a book about laws and customs published during the Heian period (794-1185). In the book, kombu is described as an offering given to the gods and the Japanese emperors. Traces of this tradition still exist today: kombu is now regarded as a lucky charm important in wedding gifts and Japanese festive food for the New Year. Roughly 95% of Japan-made kombu products are produced in Hokkaido, Japan’s second largest island and the largest and northernmost prefecture. For a long time, kombu was distributed and enjoyed across Japan via a sea route called the "kombu road".
As kombu works better with soft water in making good dashi, it was once enjoyed most widely in Kyoto, Osaka and other areas in the Kansai region, where water is particularly soft. Furthermore, as kombu is a botanical dashi ingredient, it has an important historical role in Japanese traditional vegetarian dishes, where no meat or fish is used. The Japanese food culture that surrounds dashi is deeply influenced by our climate. Therefore, katsuo-bushi is more widely used in the Kanto region whereas kombu is more popular in the Kansai region.
PRODUCTION PROCESSHow is kombu sourced and harvested?
Kombu is a variety of kelp, and it lasts two or three years. From both natural and farmed sources,
kombu can be harvested after it has been grown for two years. Artificially cultivated kombu can be harvested after one year as the culture solution accelerates its growth. Kombu harvesting is only possible between late July and early September each year. Quality kombu products with a high level of umami flavor can be made if the kombu is harvested during this period. Shortly after the kombu has been sourced from the sea, it will be either sun-dried on the beach or machine-dried. Once it is fully dried out, the kombu will be exposed to the night dew to add the finishing touches. It will then be moved indoors, flattened out, and shipped away. Natural kombu is considered a quality product, but some high-end Japanese restaurants prefer farmed kombu as this can be sourced more stably. The amount of natural kombu available on the market is subject to climate change.
- "Rausu kombu" is harvested on the coast of the Rausu region.
This area is located on the tip of the Shiretoko peninsula, which is said to be an unexplored part of the most remote area of Hokkaido. Rausu is called "the king of kombu", containing more umami flavor than the rest of the kombu varieties introduced here. The dashi extracted from rausu kombu is slightly yellowish and thick. It might not be suitable for dishes that need to be transparent, but rausu kombu dashi is widely used in Japan in making dashi, nimono (simmered vegetables and meat), and takiawase, which is a dish of meat, fish and vegetables cooked separately but served together.
- "Ma kombu" is sourced on the coast of southern Hokkaido.
The best quality ma kombu is harvested in Shirakuchi beach, Kurokuchi beach and Honbaori beach. The dashi extracted from ma kombu tastes subtly sweet, and has a tinted color. It is especially popular in the Kansai region. It goes well with tsukudani (preserved small seafood, meat, or seaweed that has been simmered in soy sauce and sugar) and nabe-mono (a traditional Japanese style hot-pot filled with broth and other ingredients).
- Harvested in the northernmost tip of Hokkaido, the "rishiri kombu" sourced on Rishiri island and Rebun island is said to be of a very high grade. Rishiri kombu does not change in quality and color. It has a rich flavor and an exquisite aroma. Since clear dashi broth can be extracted from it, many high-end Japanese restaurants in Kyoto use rishiri kombu to make ichiban-dashi, the tastiest variety of dashi. Rishiri kombu becomes sticky when it is simmered, so it goes very well with tsukemono (Japanese pickled vegetables), nabe-mono, and yu-dofu (boiled tofu).
- "Hidaka kombu" is primarily sourced in Mitsuishicho district in the Hidaka region, located in southern Hokkaido. The quality of hidaka kombu is strictly rated and depends on which beach it has been harvested from. Ikantai beach is said to be the best source for hidaka kombu. Its dashi is less sweet and clear than other varieties of kombu, but it is softer and will simmer more quickly. Therefore, hidaka kombu is suitable for making ni-kombu (kombu simmered in sweetened soy sauce). Hidaka kombu is particularly popular in the Tohoku region.
KOMBU DASHI RECIPE
"Kombu-dashi" is a broth made using kombu only. Kombu-dashi can be used when you want to make traditional Japanese vegetarian dishes and macrobiotic food in which no meat or fish is used. The best way to make good kombu-dashi is to use soft water at a temperature of around 140 - 158℉ (60 - 70℃). This will ensure that you can extract the best quality of umami flavor. The more often you make kombu-dashi, the better you will become at making it.
THE BOILING METHOD
1 liter of water / 10cm square of kombu. This can be cut a bit smaller if you are using very thick kombu.
How to make Kombu Dashi at Home
COLD BREW METHOD
The easiest way of extracting kombu-dashi is to cold-brew your kombu. Use the same amount of water and kombu as you would when extracting dashi by simmering the kombu (1 liter of water and 10cm square of kombu). Put the water and kombu into a jar, and refrigerate the jar for 10 – 12 hours. Your kombu-dashi will then be ready. But be careful: if you refridgerate the jar for more than 12 hours, this will result in slimy kombu or a harsh taste in the broth.