Pour 4 cup cold water to pot
Place kombu (dried sea kelp) in water and turn on heat to lowest setting
Bring to a low simmer and simmer for 15 minutes. Make sure the water does not start to boil
Turn off heat and add katsuobushi (dried bonito flakes)
Let it steep for additional 15 minutes
After 15 minutes, remove kombu and katsuobushi from water using a strainer or cheese cloth
Dashi is ready to use
If you are making dashi to use later, store dashi in glass container and let it cool down to room temperature before putting it in the fridge.
Dashi will keep in fridge for a week