Switch on the Instant Pot and select Saute mode. Once hot, dry roast the ingredients under "for freshly ground powder" till a nice aroma comes.
Remove and transfer these ingredients to a dry grinder jar. Grind to a powder and keep it aside.
Now in the Instant Pot, add oil. Once hot, add mustard seeds, chana dal, curry leaves, green chillies and ginger. Saute till the dal turns golden brown.
Add thinly sliced onions. Saute for a minute. Add peeled and chopped potatoes. Next, add turmeric powder and salt. Give a mix.
In a bowl, mix the water and gram flour. Add that mixture to the Instant Pot. Mix again. Ensure nothing is stuck to the bottom of the pan. Check for salt.
Cancel Saute Mode. Next, close the lid with the vent in sealing position. Pressure Cook for 10 minutes and release the pressure quickly.
Keep the Instant Pot on Saute Mode. Add the freshly ground powder. Mix well and saute for 5 minutes. If you want, gently mash the potatoes. Adjust consistency by adding water, if needed. Garnish with coriander leaves. Serve hot.