Cover pot and bring to bare simmer over med heat. Remove kombu and discard.
Add in the flakes and turn off heat. Allow to sit for about 10 minutes
Strain broth through a fine sieve. Use the stock right away or transfer into 4, 1-quart sized jars, sealing their lids. Store up to 5 days or freeze for 6 months
Video
Notes
Strained the liquid through a fine mesh sieve and discarded the bonito flakes. Used the dashi immediately or stored it in the fridge for up to 3 days.