To your instant pot's liner, add all of the ingredients, except the green onion and cheese.
Put the lid on, set the pot to sealing, and set to high pressure for 5 minutes.
When the 5 minute pressure cycle is complete, let the pot sit (naturally pressure release) for 10 minutes.
Carefully removed the lid and use an immersion blender to blend the soup.
Add the shredded cheese and onion and stir until melted and incorporated.
Taste and add additional salt, pepper, and red pepper flakes to your tastes. I find that the saltiness of a soup is dependent on the broth used. I use homemade so often need to add more salt than if I am using commercial broths.