Add 1.5 cups of water to the Instant pot and turn on SAUTE (high), so that the water comes up to a boil. Meanwhile grease your idly plates with oil or ghee, Pour idly batter into the idly plates/moulds. Do not over do.
Once the water starts to boil, place the idli stand in to the Instant pot. Close lid and keep in VENTING position and turn on 'STEAM' mode.
Steam the idli trays in the IP for 10-12 mins. Note:Timer on the instant pot does not work in the venting position, so you have to monitor time with a separate timer.
Once done, check the idlis by piercing a toothpick in it. If the tooth pick comes out clean, the idlis are done.
Remove idli's from the moulds. Serve hot, with coconut chutney and sambhar.
Notes
You can follow the same procedure to steam different varieties of idli like rice idli, rava idli, oats idli, etc.
If your idlis are still uncooked then do not worry, steam for another 2 minutes.