A method of preparing:
Pour a measured portion of rice into a large bowl and rinse it several times in cool water until it is clear. Pour clean, cold water over the washed rice and let it soak for 30 minutes. Then drain it, put it into a pot, pour a measured portion of fresh, cold water and put kombu on top.
Heat everything together over medium heat until boiling. For the first 5 minutes, cook the rice with kombu. After this time, remove the algae, reduce the flame to the smallest and cook, covered, for another 8 minutes. In the meantime, prepare the mortar. So combine vinegar, sugar and salt in a small saucepan. Heat it over low heat until the dry ingredients are completely dissolved. Set aside to cool.
Take the cooked rice from the burner and leave it covered for an additional 10 minutes. Then put it into a water-moistened hangiri or other large-surface vessel, pour it with vinegar and mix it gently so as not to damage the grains. After cooling to room temperature, the rice is ready to be molded. :)
Store in a dry, cool place.