Combine water and Kombu in a medium saucepan, and let soak for 1 hour

Then bring to a bare simmer over medium heat. Do not heat up more than 180 dregrees as Kombu turns bitter

Remove Kombu and bring water to a full boil. Kombu can be saved for use in Tsukadani

Turn off heat and once boiling has subsided, add bonito flakes without stirring. Let stand for 5 minutes. 

Strain through a fine mesh strainer and discard bonito. Do not squeeze liquid from mass of wet bonito flakes. Simply let gravity draw liquid from strainer

Dashi can be stored in the refrigerator for up to 1 week.