Set the Instant Pot to Sauté mode. Add a splash of oil and brown the beef stew meat in batches, ensuring it gets a nice sear for added flavor. Remove the beef and set it aside.
In the same pot, add the diced onion and sauté for about 2-3 minutes, or until softened. Stir in the minced garlic and sliced mushrooms, cooking until the mushrooms are tender, about 5 minutes.
Stir in beef broth, Worcestershire sauce, dried thyme, paprika, and season with salt and pepper. Scrape the bottom of the pot to deglaze, ensuring no bits are stuck.
Add the browned beef back into the pot. Close the lid, set the valve to sealing, and cook on high pressure for 20 minutes.
Once cooking time is complete, carefully release the pressure by turning the valve to venting. Stir in the egg noodles. Close the lid again, set to sealing, and cook on high pressure for an additional 5 minutes.
After the noodles are cooked, perform a quick release. In a small bowl, combine flour with sour cream to create a smooth mixture. Stir this into the beef and noodle mixture in the pot. Mix well until the sauce thickens, simmering on Sauté for an additional 2-3 minutes if needed.
Spoon the delicious beef stroganoff into bowls and garnish with freshly chopped parsley.