Select the SAUTE setting on the instant pot.Once it's hot, add oil to the instant pot.
To this, add mushrooms and saute.*
Add rest of the ingredients- onions, celery, cashew, 1 cup of water**, salt ,pepper.
Select PRESSURE COOK for 5 minutes on HIGH with the valve in SEALED position.
Once the time is over, wait for 1 minute and then Quick Release.
Open the pot and using a hand blender, blend*** into a smooth soup.Add 1 cup of water or liquid to make it thinner.
Drizzle little oil and some sauted mushrooms if desired and eat hot!