A great dashi stock is essential. It is the crucial element in soups, dipping, sauces, nimono simmered dishes and nabemono hotpot dishes, and for cooking fish and vegetables. Typically it is made from katsuobushi dried bonito or konbu kelp, or a blend of the two. Other ingredients such as niboshi dried sardines, shiitake mushrooms, and, in my kitchen tobiuo flying fish, are commonly used too.
Dashi Soup Stock
Dashi’s role in enhancing the flavour of food with that umami ‘fifth taste’ is paramount, and top chefs often guard the precise details of their dashi ingredients with a zest bordering on paranoia.
Katsuobushi is easy to spot in a Japanese market. It is the thing that looks least like fish and more like a piece of driftwood. The Japanese have been drying and curing bonito since ancient times, when the summer fish was dried to preserve it for the winter season.
Today’s katsuobushi, however, most probably dates back to 16th century Tosa now Kochi, when it was used as troop rations for itinerant samurai during the Warring States period 1477 – 1573. Superstitious warriors also enjoyed the play on words that makes ‘katsuobushi’ sound like ‘katsu-bushi’ or ‘victorious samurai’.
Superstition attaches itself to the humble bonito in several other ways. It is still a common gift at New Year and is given to teething babies so that they will develop perfect teeth. More often, though, it is grated either by hand, for dashi, using a kezuribako, similar to a carpenter’s plane, or by machine in the marketplace.
Ready-shaved katsuobushi is far more convenient. Even the use of that is considered far too time-consuming for the average Japanese homemaker, and supermarket shelves are packed with liquid and powdered varieties of varying qualities. Many are more than half decent, but making your own dashi, without chemical additives, and with full control of the ingredients, is a very useful, and I would say enjoyable, skill to have.
Konbu kelp was first harvested in Japan around the 6th or 7th century, and was an early export to China, But it was not until 1000 years later that the black, shiny ma-konbu ‘true’ or ‘proper’ konbu began to be collected in earnest on the southern and eastern shores of Hokkaidō. Its dashi became instantly successful in the Kansai region, and in particular in Kyoto, where it appealed to the Buddhist chefs preparing strictly vegetarian temple cuisine Shojin-ryori. It was especially liked for its health-giving properties and its suitability for use with tofu. Naturally, it is wholly vegan.
Over the years I have become something of a konbu obsessive. Currently sitting on my kitchen’s ‘dashi shelf’ – yes, I have such a thing – are high quality examples from Rausu, Rishiri, Rebun, Habomai, Hakodate, (all Hokkaido) and, unusually, possibly not wholly legally, kelp from the islands north of Hokkaido disputed with Russia.
One pack of my Rausu konbu is of such fine quality that it has earned the rare and much-coveted ikkyuto ‘first class’ status. Discovered by my kelp hunter journalist friend on a recent trip to Hokkaido, it cost a small fortune. I don’t know if I dare use it, to be honest!
Katsuo and Konbu stocks are both prepared in the same way. The water containing the ingredients is brought to the boil, after which the heat is immediately turned off. The flakes slowly sink to the bottom of the pan, and the liquid is filtered through a muslin sieve. It is important not to squeeze the katsuo or else the stock will become bitter. When making a tsuyu soba dipping sauce, however, a slight amount of bitterness is often considered desirable.
Traditionally, there’s a two-step process in dashi making. Ichiban dashi, the first stock, is created out of fresh materials, and is used in clear soups, to impart an aromatic element. Niban dashi is a second use of the initial ingredients – it is much lighter tasting and is used with miso soup, and in nimono and vegetable preparation.