Soak the kombu in water for at least 2 hours and up to overnight
Gently heat the kombu to a simmer for 15 minutes or until the kombu is tender. Do not boil
Remove the kombu from the water and discard
Bring stock to a boil, and add bonita flakes. Let boil one minute and remove from heat. Let stand 5 minutes and then strain out flakes through a coffee filter placed in a fine mesh strainer