Slice the onion, garlic and celery. Place all of the veggies in the Instant Pot bowl along with the olive oil. Press the ‘saute’ button and cook for 5 minutes, stirring occasionally.
Add the potatoes, vegetable stock, salt and pepper to the bowl and stir. PLace the Lid on the Instant Pot and set the steamer valve to ‘seal’. Press the ‘manual’ button and set the timer for 10 minutes, cooking on high pressure.
When the cooking cycle is complete, do a natural pressure release by letting the pot just sit, allowing the steam to slowly release. In about 15 minutes, you should be able to open the lid!
Use a hand mixer or blender to puree the soup until smooth.
Serve the soup while warm or let it cool and serve as a chilled soup on a hot day. Enjoy!