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  • 2 4-inch squares of kombu
  • 2 ½ quarts water
  • ½ ounce bonito flakes (~ 2 cups)


  • Put the kombu in a 4-quart saucepan, cover with the water and soak for 30 minutes.
  • Set the saucepan over medium heat until the water reaches 150 to 160 degrees F and small bubbles begin to appear around the sides of the pan (~ 10 minutes)
  • Remove the kombu from the pan
  • Increase the heat to high and bring to a boil (~ 5 to 6 minutes)
  • Reduce the heat to low and add the bonito flakes. Simmer gently, stirring frequently, for 10 minutes
  • Strain the liquid through a fine mesh strainer lined with muslin or several layers of cheesecloth
  • Store in an airtight container in the refrigerator. Use within a week or freeze for up to a month