Sauté Beef: In a large frying pan over high heat, add 2 tablespoons of olive oil and the beef along with a big pinch of salt. Sauté until it has some colour on all sides, then remove and set aside.
Cook Mushrooms: Place the pan back over high heat with some more oil and add the mushrooms along with a pinch of salt and some fresh black pepper. Cook for 2-3 minutes until they start to have some colour, then set aside.
Sauté Onions: Place the pan back on high heat with some more oil and add the onions with a pinch of salt. Sauté for 2-3 minutes.
Combine and Cook: Add the beef stock, scraping the bottom of the pan to get all the fond, then add the beef and mushrooms back to the pan along with the Worcestershire sauce. Stir well.
Thicken Sauce: Stir in the flour to thicken and continue to cook so the flour cooks out for 5-6 minutes.
Prepare Egg Noodles: Cook the egg noodles in salted boiling water for 3-4 minutes or until cooked through, then drain well and add back to an empty pot with the butter to coat the noodles.
Finish and Serve: Finish the beef with the sour cream and chopped parsley. Serve the beef stroganoff over the egg noodles.