Turn the instant pot to saute (normal) and add the sliced onions. Fry them until reddish brown.
Add the wet masala, tomatoes, and ground spices. Cook for 10 minutes or until the tomatoes break down.
Add the lamb and salt and cook for 5 minutes more, stirring the contents with a spoon every now and then. Add a few splashes of water if you see the masala getting dry.
Add 2 cups water and cancel sauté.
Secure the lid, press the pressure cooking button (high), set the timer to 15 minutes and make sure the steam release handle is sealed.
Once the timer beeps, wait for 10 minutes, then release steam by turning the steam release handle to venting.
Open the cooker and add the potatoes. Again, secure the lid and set the cooker to one minute pressure.
When the timer beeps, open the cooker and add green chillies and cilantro. Serve aloo gosht with warm naan.