Bring a pot of water to a boil and cook the egg noodles according to package directions until tender, then drain and set aside.
Slice the beef into thin strips and season evenly with the sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat until shimmering.
Add the beef strips to the skillet and sear until browned on all sides, then remove from the pan and set aside on a plate.
In the same skillet, add the sliced mushrooms and diced onions, sautéing until the vegetables are golden and tender.
Stir in the minced garlic and cook for 30 seconds until fragrant.
Pour in the beef broth to deglaze the pan, using a wooden spoon to scrape up any flavorful browned bits from the bottom.
Reduce the heat to low and stir in the Dijon mustard and Greek yogurt until the sauce is smooth and creamy.
Return the cooked beef and any accumulated juices to the skillet, tossing to coat the meat thoroughly in the sauce.
Serve the beef and mushroom mixture over the warm egg noodles and garnish with chopped fresh parsley.