Bring a pot of salted water to a boil and cook the egg noodles according to package directions until al dente, then drain and set aside.
Season the beef sirloin strips with half of the sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat and sear the beef until browned on all sides, about 2-3 minutes, then remove from the pan and set aside.
In the same skillet, add the sliced mushrooms and diced onions, sautéing until the mushrooms are golden and onions are translucent.
Add the minced garlic to the skillet and cook for 1 minute until fragrant.
Pour in the beef bone broth, Dijon mustard, and Worcestershire sauce, scraping the bottom of the pan to release any browned bits.
Lower the heat to a simmer and let the liquid reduce by half, about 5 minutes.
Remove the skillet from the heat and stir in the Greek yogurt until the sauce is smooth and creamy.
Return the beef and any accumulated juices to the skillet, stirring to coat in the sauce.
Season with the remaining salt and pepper to taste.
Serve the beef and mushroom mixture over the cooked egg noodles and garnish with freshly chopped parsley.