Turn on saute mode on the Instant Pot, and heat the oil.
Add the onion, and saute until light golden at the edges.
Add the tomatoes and saute for 1 minute.
Add the spices and saute for 1-2 minutes.
Now add the water, and using an immersion blender, blend the tomato onion masala until smooth.
Cook for another minute.
Add the mushrooms and mix.
Cancel saute mode, put on the lid of the instant pot. Make sure the pressure valve is pointing towards sealing. Set the pressure cook mode manually to 4 minutes.
After the pressure cooking is complete, do a quick release by moving the pressure valve to venting.
Remove lid, and turn on saute mode.
Add peas and cook for 2-3 minutes until cooked through.
Now mix through the heavy cream.
Serve with rice or garlic naan.