Get the water started for the pasta. (Optional: Salt water 1 to 2 tsp). Get all ingredients in place.
Finely dice the onion and mince the garlic. Cut the beef in thin strips or small bite-size pieces. Season with salt and pepper.
Add the egg noodles to the boiling water and cook according the package instructions. (usually 6 to 8 minutes depending on how firm you like it). Remove it to a colander when it's done.
Meanwhile, as the noodles cook, heat a large skillet (preferably cast iron, but any large deep skillet will do) on medium high. Add 2 teaspoons of olive oil and sauté the onions for about 2 to 3 minutes, or until they begin to soften, stirring regularly.
Add the beef to the onions in the skillet. Allow to cook at least a minute or so without stirring so the beef gets a good sear, then flip / stir and cook about about 2 more minutes or until it's cooked, stirring occasionally. (It's ok if it's still slightly rare in spots)
Add the garlic and stir. Add the mushrooms and cook about 2 to 3 more minutes, or until the mushrooms soften, stirring occasionally.
Sprinkle the flour over the beef, mushrooms and onions and stir.
Reduce heat to medium-low. Add the dijon mustard, Worcestershire sauce, low-fat sour cream, and beef broth/stock then stir until it all mixes together.
9. Add additional salt, pepper, and herbs to taste, and stir. Let it all simmer for about 3 more minutes or until all ingredients are thoroughly and evenly heated.
Stir the cooked egg noodles right into the beef and sauce mixture, or serve a portion of noodles and spoon the sauce on top.
Optional: Garnish with fresh parsley.
Optional: add 1 tsp Xanthan gum to thicken.