Step 1

To make the sushi vinegar, briefly and gently wipe the kombu with a damp towel to remove any dirt or grit, but do not scrub off the white stuff, which is full of umami.

Step 2

Combine the vinegar, sugar, salt and kombu in a small saucepan and set it over medium-high heat. Cook, stirring often, just until the sugar has dissolved, about 1 minute. Do not let it boil. Let the mixture cool to room temperature.

Step 3

Measure 1/2 cup (4 fl. oz./125 ml) of the vinegar mixture and set it aside. Store the rest, including the kombu, in an airtight container in the fridge for up to several months.

Step 4

To make the rice, put the rice in a large mixing bowl and add enough water to cover the rice by 1 inch (2.5 cm). Use your hands to stir and agitate the rice to release the starch from the exterior of the grains. Empty the water, fill the bowl again and repeat the process until the fresh water no longer becomes cloudy when you stir the rice. Drain the rice in a mesh strainer, shaking well to help drain any excess water. Let the rice sit in the strainer, stirring it once or twice, until it’s more or less dry to the touch, 15 to 30 minutes.

Step 5

Combine the rice and 3 cups (24 fl. oz./750 ml) fresh water in a rice cooker and cook according to the manufacturer’s instructions.

Step 6

While the rice is hot, gently scoop it into a bowl. Sprinkle the reserved 1/2 cup sushi vinegar over the rice. Gently fold the rice to make sure the vinegar is well distributed without smashing the grains. Cover with a clean kitchen towel pressed to the surface of the rice and let the rice cool to just slightly above room temperature before using. Makes about 8 cups (2 1/2 lb./1.25 kg) rice.

Step 7

Adapted from Mastering the Art of Japanese Home Cooking, by Masaharu Morimoto (Ecco, 2016)