Heat a large Dutch oven or heavy-bottomed pot over high heat.
Add the cubed sirloin and chopped onion. Sear until the beef is browned on all sides and the onions are soft, about 5–7 minutes.
In a medium bowl, whisk together the cream of mushroom soup, milk, red wine, and beef with onion soup mix until smooth.
Pour the soup mixture over the browned beef and onions in the Dutch oven. Stir to combine thoroughly.
Bring the mixture to a gentle simmer, then reduce the heat to low. Cover and cook until the beef is tender, about 4 hours.
While the beef is cooking, prepare the egg noodles according to the package directions. Drain and set aside.
Once the beef is tender, stir the cooked egg noodles into the beef and creamy sauce mixture until everything is evenly combined.
Serve immediately, garnished with fresh parsley if desired.
Enjoy!
