How kombu is made

As with dashi made from other ingredients, the time it takes to make kombu dashi is short while the dried kombu making process is rigorous and time consuming.

Kombu thrives in the cold waters off Hokkaido in the north of japan, tending to inhabit waters around five to eight metres deep and generally takes around two years to reach the level of maturity required for harvesting. By this time the fronds can be anything up to six metres in length.

Harvesting usually only takes place during the summer months of july to September, on dates determined annually, and is traditionally carried out by kombu harvesters in boats. They use long wooden poles with hooks attached to detach the kombu from the seabed at the root. As soon as the kombu reaches dry land, it is laid out on rocks to dry. On a sunny day, this process can be completed in four or five hours. Once dry, the kombu is taken indoors, the shape of each frond is adjusted and then it is dispatched. Alternatively, some kombu undergoes a further maturation process known as kuragakoi (cellar conservation). This process, which is explained in more detail on the opposite page, improves the flavour of the kombu and removes its distinctive seaweed odour.