Slice the onions and potatoes into medium sized pieces and add them to the instant pot. Chop the tomatoes in small or medium sized pieces and add this also to the inner pot.
Add the garlic, ginger, green chilies and enough salt, mix everything well.
Add the water and all spice powders, mix everything well. Also add the oil and gently stir in.
Close the instant pot with lid on sealing position, press the manual button and cook in high pressure for 5 minutes.
Once the cooking is done, wait for a natural pressure release. If neccesary, you may do a gradual, controlled manual pressure release after about 12 minutes of natural pressure release to release any remaining pressure.
Once the pressure is all released, carefully open the lid of the instant pot and stir the contents very well.
Using the saute function, you may simmer the curry for another couple of minutes until desired thickness is reached. If using the coconut milk or heavy cream, add it now and stir in with the curry for a creamy texture.
To add the garnishing, you can add the chopped cilantro leaves or fresh curry leaves, gently mix in with the curry. Serve the potato curry hot with rice, chapathi, poori or enjoy with whatever you like to serve it with.