Cut the steak into thin strips and dredge them in flour seasoned with salt and pepper. Heat up a good sized frying pan or large saucepan and quickly flash fry the steak in the oil to brown the strips all over, remove the steak from the pan and set aside. Lower the heat then gently fry the onions for a few minutes before adding the minced garlic. Next in go the butter and mushrooms. The butter soaks into the mushrooms and adds an extra layer of luxury but, if you want to lower the calorie count slightly, just use more oil, if needed.
When the mushrooms have softened add a little of the beef stock and deglaze the pan, or scrape all the lovely bits stuck to the bottom if you prefer. Add the remaining stock and return the steak pieces to the pan. Stir in the sour cream and mustard. Let it simmer for 5 or ten minutes and check the seasoning. Add more salt and pepper if you think it’s needed.
Serve it up with carbs of your choice, mashed potatoes are good for me but rice, pasta, skinny fries or whatever you like will work just as well. Garnish with parsley for colour and flavour and enjoy.
Your guests and your stomach will thank you.