In a large bowl, toss the beef with salt, pepper, and 1/4 cup flour to lightly coat.
Heat the oil in a large, high-walled skillet over medium-high heat. Working in batches, sear the beef on one side until it develops a deep brown crust, then flip and sear on the other side, about 8 minutes total. Remove the beef from the pan and repeat with the remaining meat.
Melt the butter in the pan and reduce heat to medium. Add the onions, garlic, bay leaf, sprig of thyme, and a sprinkle of salt and pepper and cook until the onions are soft and nearly caramelized, about 20 minutes. Add in the mushrooms, and saute until the mushrooms are soft and slightly browned and the onions have caramelized, about 5 more minutes. Discard the bay leaf and thyme.
Deglaze the pan with the red wine, being sure to scrape up all of the browned bits. Sprinkle with the remaining flour and stir to combine. Stir in the beef broth and Worcestershire sauce and bring to a low simmer. Mix the beef back in and let simmer until the sauce has thickened and the beef is cooked through, about 8 minutes.
As you wait for the sauce to thicken, cook the egg noodles according to the package. Drain and set aside.
Remove the beef mixture from the heat and add in the 2/3 cup of sour cream, stirring well. Mix in the cooked egg noodles.
Top with the grated Gruyere. If in a ovenproof pan, bake in a 400°F oven until cheese is melted and slightly browned. If not, leave the pan on the burner on medium-low, cover, and heat until cheese melts.