Cut the beef into strips, across the grain. Make them about 1½ by ½-inch (3¾ by 1¼ cm).
Sauté the onions, garlic and mushrooms in the butter over a moderate heat until the onion is tender, stirring occasionally.
Remove the sautéed vegetables to a dish.
Cook the beef in the same pan until golden brown, then stir in two-thirds of the broth, as well as the Worcestershire sauce and salt.
Bring the mixture to a boil, then turn down the heat.
Cover and simmer gently for 10 minutes.
Meanwhile you can cook the egg noodles (or rice if you prefer that).
Stir the rest of the broth into the flour, then stir this into the beef mixture.
Add the onion mixture back in, and bring the stroganoff to a boil, stirring all the time.
Cook for 1 minute then stir in the sour cream and warm it through (don’t let it boil again).
Serve hot, over the hot egg noodles, garnished with cream and parsley if liked.
