Bring a large pot of salted water to a boil, add the egg noodles, and cook according to package directions until just tender. Drain and set aside.

Pat the beef strips dry with paper towels, then season with 1/2 teaspoon of the fine sea salt and 1/4 teaspoon of the freshly ground black pepper.

Sprinkle the all-purpose flour over the seasoned beef and toss gently until the beef strips are lightly coated on all sides.

Heat the olive oil in a large wide skillet over medium-high heat. Add the floured beef in a single layer (cook in batches if needed) and sear for 2 to 3 minutes, just until browned on the outside. Transfer the browned beef to a plate and set aside.

Reduce the heat to medium and add the unsalted butter to the same skillet. When melted, add the sliced yellow onion and cook for 3 to 4 minutes, stirring often, until the onion starts to soften.

Add the sliced mushrooms to the skillet with the onion and cook for another 5 to 6 minutes, stirring occasionally, until the mushrooms release their juices and turn golden in spots.

Stir in the minced garlic and cook for 30 seconds, just until fragrant, being careful not to let it brown.

Add the Dijon mustard and smoked paprika to the skillet and stir well to coat the onions and mushrooms evenly with the seasonings.

Pour in the beef broth and use a wooden spoon to scrape up any browned bits from the bottom of the skillet. Bring the mixture to a gentle simmer and cook for 3 to 4 minutes to slightly reduce the sauce.

Reduce the heat to low, then add the sour cream to the skillet. Stir slowly and continuously until the sour cream is fully incorporated into the sauce and the mixture is smooth and creamy. Do not let it boil.

Return the browned beef and any accumulated juices on the plate to the skillet. Stir to coat the beef in the sauce and simmer on low heat for 3 to 4 minutes, just until the beef is heated through and tender.

Season the sauce with the remaining 1/2 teaspoon fine sea salt and 1/4 teaspoon freshly ground black pepper, or to taste, and stir in the chopped fresh parsley.

Serve the Beef Stroganoff over the cooked egg noodles, spooning plenty of sauce, beef, onions, and mushrooms over each portion.