Turn on the Instant pot to Saute mode. When it is hot, melt butter.
Add crumbled sausage and brown until aromatic. for about 2 minutes.
Add chopped onion, celery, minced garlic, carrot. Saute for 2-3 minutes. to soften onion.
Add diced potatoes, thyme, basil, red pepper flakes, stock, and salt.
Give everything a good stir. Scrap the bottom of the pot to release any stuck brown bit.
Close the lid, place the valve to 'sealing', and set Instant pot to high pressure for 8 minutes.
When the timer is off, let the pressure release naturally for 10 minutes. Carefully release rest of the pressure.
With the back of the ladle gently pres a few chunks of potatoes(to thicken the soup).
If you prefer a thinner consistency, add 1/2 cup stock more.
Stir in sour cream.
While serving top with crispy bacon, shredded cheese, and green onion.