the same amount as the citrus juice and vinegar combined
a small amount
a 3 cm square piece
Wash the daidai or yuzu, cut in half and squeeze out the juice. Don't worry about a little pulp getting in the juice. Put the juice into a large measuring cup.
Add an equal amount of vinegar. If there is 100 ml of citrus juice, add 100 ml of vinegar. Put into a container and store. In the winter you can leave it out at room temperature.
To make ponzu soy sauce, add an equal amount of soy sauce - for example, for 50 ml of the base, add 50 ml of soy sauce. Add sugar, umami seasoning and the konbu seaweed pieces, and leave to marinate for about 2 hours.
Story Behind this Recipe
If using yuzu, thinly shave the zest off after juicing the fruit, cover with plastic wrap, put into a plastic bag and freeze. The seeds can be soaked in shochu, to use as facial skin toner. There's nothing to throw out. You can also use kabosu or sudachi citrus. For eating puffer fish, daidai is good. Try ponzu sauce on rice porridge or pickled Chinese cabbage.
I make a lot of the the base, so I make 1 cup of juice plus an equal amount of vinegar and turn it into ponzu soy sauce as needed. I divided any leftover citrus juice only into small portions, and froze it in plastic bottles or plastic bags. It's much better to make ponzu soy sauce when needed since the soy sauce loses its flavor quickly.