Wash and rinse the rice for a few times until the water is almost clear. Drain and sieve any excess water.
Add the rice to the rice cooker or pot and pour in the water (the rice to water ratio should be 1:1). Place the kombu on top of the rice and let the rice soak in the water for 30 minutes. Then, start cooking.
In a small bowl, mix the rice vinegar, sugar, and salt together. Set aside.
When the rice is ready, wet your paddle so that it doesn’t stick to the rice. Pour the sushi vinegar over the rice and mix using the paddle. Cover the rice with a damp towel until it comes to room temperature.