Place the rice into a mixing bowl and add just enough water to cover it. Use your hand to stir the rice in the water 2-3 times and then drain. Repeat this process until the water is almost clear.
Place the rice in the Instant Pot, add the water and kombu (kelp) if using.
Cook on high pressure for 2 minutes and leave on natural release for 10 minutes.
Meanwhile make the sushi vinegar by combining the rice vinegar, sugar, and salt in a small pot over medium heat until the sugar and salt dissolve.
Discard the kombu if using, transfer the rice to a mixing bowl or hangiri and pour on the sushi vinegar.
Use a wooden spoon, spatula or rice paddle to gently fold the vinegar together with the rice. If you want you can gently fan the rice as you do this to cool it down.
Repeat this process until the rice has cooled to body temperature.
If you are not using the rice straightaway cover with a damp tea towel to prevent it from drying out.
Video
Notes
Japanese short grain rice: Is often labeled as 'sushi rice'. You should be able to find it in regular stores. You can also buy Japanese Rice (sushi rice) online from Amazon or an Asian grocery store.
Kombu: Is a type of dry kelp (seaweed) that adds umami (savory) flavor to the rice. You probably won't find it in a regular store so you'll need to buy kombu online or from an Asian grocery store.
Rice Vinegar: You can substitute with apple cider vinegar.