First, prep your ears of corn. If you bought your corn fresh from a farmer's market (or got it from your own garden!), then take the time to thoroughly remove the husks and corn silk.
Place the metal trivet in the bottom of the pot, and add a cup of water. It won't seem like much water, compared to boiling the corn in a big pot of water, but remember - you're using steam to cook the corn.
Arrange the ears of corn on top of the trivet. You can do this in two ways. Either place all the corn upright, with the base of each ear of corn resting on the trivet and the top tips facing up. Or, layer the corn in rows. Typically each row will consist of 3 ears. Place 3 ears facing one direction, and another layer of 3 ears running perpendicular.
Place the lid on your Instant Pot, and make sure that the steam release valve is in the sealing position.
Set the pressure cooking time to 2-3 minutes at high pressure. It will take about 10-12 minutes for the Instant Pot to come up to pressure, and then the cooking time will start.
As soon as you hear the timer go off, immediately move the steam release valve to the venting position, for a quick pressure release.
Once the quick release of the remaining steam has finished, open the lid and enjoy your perfect corn!