Boil some water and cook the pasta while you are preparing the stroganoff. When it is cooked, drain and set aside, covered, to keep warm until ready to serve.
Heat oil in a heavy skillet over med-high heat. Add steaks, sprinkle generously with salt and pepper. Fry till they have some nice brown areas. Flip and fry second side. The time will vary according to how thick your steaks are. Internal temperature should be 125°. Fry to your desired doneness. Remove from skillet and place on plate for later. Internal temperature should be 125°.
Add butter and onions to skillet. Turn heat to medium. Stir and scrape up browned bits, cooking till onions are soft but not burned.
Add mushrooms and simmer for about 5 minutes, until mushrooms are soft.
Add broth and garlic, stir and simmer for 2 minutes.
Add the steak back into the broth. Add the sour cream, mustard, and parsley. Stir until hot and beginning to bubble. Do not boil!
When hot, remove from heat and serve over cooked pasta.
Notes
Note: This recipe uses half a box of pasta. If you are serving hearty eaters, you may need to use the whole box of pasta.You may use different types of pasta. Egg noodles are commonly used in this recipe.Steaks can be cooked to your desired doneness. Thicker steaks may be used, adjust frying time as needed. Less sour cream may be used, if desired. 1/2 a cup is fine, just not quite as creamy.