Step 1

Pour soy sauce and mirin into a small saucepan over high heat.

Step 2

Bring it to a boil and then turn the heat off in order to evaporate the alcohol content of the mirin.

Step 3

Add kombu strip and bonito flakes to the saucepan while the mixture of soy sauce and mirin is still hot.

Step 4

When it has cooled down, add a citrus juice of your choice.

Step 5

Place it in refrigerate overnight.

Step 6

Strain the ponzu sauce with a fine mesh strainer and pour it into a sterilized jar.