Step 1

Place the water and kombu in a large saucepan and leave to soak for at least 30 minutes.

Step 2

After 30 minutes, start to gently bring the water to the boil over a medium-high heat. Just before it reaches boiling point—when small bubbles appear at the bottom of the pan—remove the kombu and continue heating. Once boiling, turn the heat off and sprinkle the katsuobushi (bonito flakes) into the kombu dashi. Leave to brew for 2 minutes, letting the flakes sink to the bottom of the pan.

Step 3

Strain the dashi through a muslin/cheesecloth or paper towel-lined fine-mesh sieve/strainer, letting it drip through. The finished dashi will keep in the refrigerator in a sealed container for up to 3 days.