Cook egg noodles according to the directions on the package, I recommend cooking them by when you are almost done with the beef sauce.
Season salt with salt and pepper.
In a large pan, over medium heat melt butter. Add steak in a single layer and cook for 2-3 minutes per side, until browned. (Work in batches, if your pan isn't big enough).
Remove cooked steak from the pan and transfer to a plate
Add onions, mushrooms, and garlic. Cook for 5-6 minutes, until tender, stirring frequently, add more butter (1-2 tbsp), if needed.
Add wine and stir to deglaze the pan. Add stock, Worcestershire sauce and flour. Stir to combine. Cook for about 5 more minutes, stirring frequently until the sauce thickens. Add sour cream (or heavy cream). Cook for just 1 minute, to warm up.
Season with salt and pepper. Garnish with parsley.
Serve over egg noodles.