Dashi is a basic soup stock for many Japanese dishes. Some of the recipes on this site need dashi as a basis.
Put the kombu and water in a pot. Soak the kombu for approximately 10 to 15 minutes. Heat the water over medium heat. Just before the water starts boiling turn off the heat and remove the kombu. Then add the bonito flakes. Wait until the flakes sink to the ground (or for around 15 minutes). You may remove flakes by passing the liquid through a coffee filter or a strainer.