Soak cashews in ½ cup warm water for 10 minutes and set aside. Drain all the water and blend the cashews with ¼ cup of water to make smooth paste and reserve.
Set the Instant Pot to saute mode and heat add ghee. Add onions and cook for 3 to 4 minutes with a glass lid on, stirring a few times. Add ginger and garlic paste, cook for 30 seconds. Turn the Instant Pot off.
Add tomato puree, turmeric, red chili powder, garam masala salt, and mushrooms. Mix well, deglazing the pot to remove any browning on the bottom of the pot. Close the Instant Pot, and pressure cook(Hi) for 4 minutes followed by Quick Release.