Season meat with 1 1/2 teaspoons salt and 1 teaspoon pepper. Toss to evenly coat.
Turn a 6.5-quart Instant pot onto saute function. Add vegetable oil. When the display reads "hot". Add the beef in batches, in a single layer, and brown. Remove to a plate. Repeat process with additional oil as needed and remaining beef.
Melt the butter then add the onions, garlic, and mushrooms to the Instant pot and saute, until soft, about 3 minutes. Sprinkle the vegetables with flour and stir to coat.
Add the sherry and 1/2 a cup of beef broth to the pot, stirring, gently scraping the bottom of the pot with a wooden spoon to loosen all brown bits on the bottom of the pan (do not skip or the burn light may turn on). Allow to reduce for 2 minutes.
Add remaining beef broth, soy sauce, Worchestershire sauce, mustard, tarragon, and thyme stirring, until combined. Add browned beef along with any juices that have accumulated on the plate.
Lock the lid and set the valve to seal. Set function to "manual mode-high pressure" for 15 minutes. The instant pot will start on its own.
Switch the valve to the "venting" position to quick release for 10 minutes.
Stir in egg noodles and set function to "manual mode-high pressure" for 3 minutes. Do another quick release. Turn off the Instant Pot, remove lid, let sit for 5 minutes.
Stir in sour cream, adjust seasoning with salt and pepper as needed. If sauce needs to thicken more, set Instant Pot to soup setting and stir occasionally until sauce thickens to desired thickness.
Ladle into individual bowls, sprinkle with parsley and serve.