Place the sushi rice in a large bowl and wash the rice under running cold water until the water comes out clear. → Move the rice in a circular rotation using your hand to speed up this process.
Carefully discard the water (use a sieve if you want) and generously fill the bowl with fresh cold water. Let the rice soak for 30 minutes.
Drain over a sieve, place the rice in a rice cooker, add 2 ⅓ cups of water, and switch on the rice cooker.
Once cooked, switch off the rice cooker (unplug if necessary, don't leave it in the "warm" mode) and leave the rice for another 30-45 minutes in the rice cooker with the lid on. → This step can be skipped if in a hurry, but it does make a distinguishable difference!
Meanwhile, add rice vinegar, sugar, and salt in a small saucepan. Bring to a boil, switch off the heat, and stir until the sugar has dissolved.
Place the sushi rice in a large bowl, pour over the hot vinegar mixture, and toss until well combined. Cover with a damp tea towel and let it cool to room temperature before using it for sushi.