Rinse the rice using a sieve over a large bowl, swishing it in cold water until the water is cloudy. Drain and repeat twice more.

Soak the rinsed rice in a rice cooker or pot with 350 ml of cold water and 5 g of kombu for 30 minutes to 1 hour.

Cook the rice according to your rice cooker's sushi setting, or for stovetop, add 1 tbsp sake after soaking and bring to a boil covered, without lifting the lid.

After 30 seconds of boiling, reduce heat to medium-low for 2 minutes, then low for 5 minutes. Raise heat to high for 10 seconds, then turn off and let sit for 10 minutes undisturbed.

While the rice is steaming, mix 1 tbsp sugar, ½ tbsp salt, and 2 tbsp rice vinegar until dissolved.

Once steaming is complete, gently transfer rice to a sushi oke or wide container, avoiding scraping the bottom of the pot. Pour the vinegar mixture over and fold gently with a rice paddle, fanning to cool.

Spread rice into a thin layer to cool quickly. Use immediately or cover with a damp tea towel to prevent drying.