Prepare the Beef: Pat the beef strips dry with a paper towel and season generously with salt and pepper. This helps to get a fantastic sear. Heat the olive oil in a large, heavy-based frying pan or casserole dish over a medium-high heat.

Sear the Beef: Working in two batches to avoid overcrowding the pan, sear the beef strips for 1-2 minutes on each side until nicely browned. Don't cook them all the way through at this stage. Remove the beef from the pan with a slotted spoon and set aside on a plate.

Sauté the Aromatics: Reduce the heat to medium. Add the butter to the same pan. Once it’s melted, add the chopped onion and cook for 5-7 minutes, stirring occasionally, until softened and translucent. Add the minced garlic and cook for another minute until fragrant.

Cook the Mushrooms: Add the sliced mushrooms to the pan and increase the heat slightly. Cook for about 8-10 minutes, allowing them to release their moisture and then brown nicely. This step is crucial for developing a deep, earthy flavour. I find that letting them sit without stirring for a few minutes at a time helps them caramelise better.

Build the Sauce Base: Sprinkle the smoked paprika and plain flour over the mushrooms and onions. Stir well and cook for 1 minute to cook out the raw flour taste.

Deglaze and Simmer: Gradually pour in the beef stock, stirring constantly to avoid lumps. Bring the mixture to a gentle simmer, scraping the bottom of the pan to lift any browned bits – this is where so much flavour lies! Let it simmer for 3-4 minutes until the sauce has thickened slightly.

Cook the Noodles: While the sauce simmers, cook the egg noodles in a large pot of salted boiling water according to the package directions. Once cooked, drain well.

Finish the Stroganoff: Reduce the heat under the sauce to low. Stir in the Dijon mustard. Return the seared beef and any accumulated juices to the pan. Let it warm through for a minute. Take the pan off the heat completely and let it cool for a moment before stirring in the soured cream. This is the most important step to prevent the sauce from splitting.

Serve: Season the stroganoff with salt and pepper to taste. Serve the creamy beef stroganoff immediately over the warm egg noodles, garnished with a generous sprinkle of fresh parsley.