Bring a large pot of salted water to a boil. Cook egg noodles according to package directions. Drain once the noodles have finished cooking.
In a large bowl, stir together the flour, salt, and pepper. Add the steak slices and toss to coat. (Save any flour left in the bowl.)
Place a large skillet over medium-high heat. Add the olive oil and brown the steak strips in batches. Remove to a bowl and set aside.
In the same skillet, melt the butter. Turn the heat down to medium and cook the onions until soft and translucent.
Add the mushrooms and garlic and cook for 2 minutes, stirring often.
Add the remaining flour to the skillet and stir into the veggies. Pour in the beef broth and stir continuously to prevent any lumps from forming.
Add the Dijon, thyme, and Worcestershire sauce and stir to combine. Cook for 4 minutes until the sauce thickens.
Add the steak back into the sauce and cook until the beef is heated through. Remove skillet from the heat and stir in the sour cream.
Serve the sauce over hot egg noodles and garnish with chopped parsley.