Set your Instant Pot to the sauté function. Once hot, add the ground beef and diced onion. Cook until the beef is browned and the onion is translucent, about 5 minutes. Drain excess fat if needed.
Stir in the minced garlic and sliced mushrooms. Cook for an additional 2 minutes until the mushrooms are softened.
Add the beef broth, Worcestershire sauce, thyme, paprika, and season with salt and pepper to taste. Stir well to combine.
Add the egg noodles on top of the mixture but do not stir. Just press them down gently into the liquid.
Close the Instant Pot lid securely and set the valve to the sealing position. Select the manual or pressure cook setting on high pressure for 5 minutes.
After the cooking time is complete, carefully do a quick release of the pressure by turning the valve to the venting position. Once the pressure is fully released, carefully remove the lid.
Stir in the sour cream until well combined and creamy. If necessary, adjust the seasoning with additional salt and pepper.
Serve hot, garnished with chopped fresh parsley if desired.