Dry the pork tenderloins thoroughly, then season with garlic salt, pepper and smoked paprika. Rub spices evenly into the pork, and cut in half (so they fit into the pot).
Heat the Instant Pot on SAUTE. Pour the olive oil into the pot when HOT. Add the pork pieces to the pot and brown on all side. Remove from pot and set aside.
Add the butter to the pot. When melted, saute the mushrooms until browned. Pour in the sherry to deglaze the pot. Scrape any browned bits off the bottom.
Place the pork on top of the mushroom in an even layer, then dot with dollops of the cream of mushroom soup. Set the Instant Pot for HIGH pressure for 10 minutes. Allow to naturally release.
When the pin has dropped, open the lid. Remove the pork and set aside. Whisk in the sour cream. Return the pot to SAUTE; bring the sauce to a simmer until thickened. If desired, you can whisk in 2 tablespoons of cornstarch to aid in thickening.
Slice the pork and serve topped with mushroom sauce.