In a large skillet, over medium-high heat, add the butter, cubed beef pieces, and chopped onion. Cook the onions, and pieces of beef, until the meat is lightly browned on all sides. This will take 7 to 9 minutes. It is ok if there is still some pink to the meat as it will continue to cook in the liquids.
Once the meat is browned, add to the skillet the unsalted beef broth, can of French onion soup, the contents of the packet of beefy onion soup mix, salt, black pepper, and fresh chopped parsley. Lower the heat to medium and allow the meat to simmer for 10 minutes.
Once the meat has simmered, stir in the egg noodles.
Bring the liquids up to a boil, then reduce the heat to medium-low, cover the skillet with a lid and allow the noodles to cook for 10 to 12 minutes or until soft. Check the noodles about halfway through cooking and stir them if needed. Be sure that all the noodles are in the liquids.
Once the noodles are cooked, remove the lid from the skillet, turn off the heat and stir in the sour cream until you get a nice thick sauce.
Sprinkle the crispy fried onions over the top of the French onion beef noodles and add an additional sprinkle of fresh chopped parsley, if desired to garnish.
I like to trim any excess fat from the cut of London broil beef before cutting it into cubes. It will sometimes have a piece of “silver skin” on the side that is tough to chew when cooked.
Searing the meat before adding the broth will lock in the flavor and juices, resulting in tender and delicious beef.
Make sure to note that you are adding the egg noodles UNCOOKED to the skillet. They will cook while simmering in the broth.
This dish is best served immediately. As the noodles sit, they will continue to absorb the sauce.