Cook egg noodles according to package directions, drain and set aside.
Season steak generously with salt and pepper; sear in a hot skillet 3–4 minutes per side for medium, then transfer to a plate.
In the same skillet, sauté sliced mushrooms in butter until golden, then stir in sour cream, beef broth, and thyme until combined.
Slice steak and return to the skillet with noodles, tossing gently to coat, and serve warm.