1Cut small slashes in it to help release of flavor and add to pot of water.
2In a medium sized pot, bring water with the kombu slowly to a boil, do not actually boil or it will discolor dashi and make it bitter.
3As the water comes to a fast simmer and just before the boil, remove the kombu from the water and add the bonito flakes.
4Turn the heat off and leave the pot uncovered for 20 minutes.
5The bonito flakes will fall to the bottom of the pan when the dashi is ready to be strained.
6If the bonito flakes are still suspended after 20 minutes, leave the pot until they have fallen (this process usually takes only 20 minutes but bonito flakes can vary in moisture content and the process could take a few minutes longer. Just know that you are looking for the flakes to fall before straining). Use a fine mesh strainer to strain the bonito flakes out of the dashi.
7Save the flakes to make a second dashi stock if required.
8Use stock for noodle or soup dishes.