konbu is the basic dashi ingredient.To make good stock, simply soak konbu in water, or heat in a pan of water on a medium flame and remove just before boiling. To make dashi konbu, Kelp is dried in the sun, and then wrapped in straw mats. konbu is rich in vitamins and minerals such as iodine. It also contains large quantities of potassium, which helps to reduce blood pressure. The best-known konbu-producing districts in Japan are Hidaka and Rausu in the northern island of Hokkaido. konbu is not only used for dashi, but also for tsukudani and tororo.