Brown the Beef: Heat vegetable oil in a large skillet or Dutch oven over medium heat. Add beef pieces and brown on both sides. Remove the beef from the skillet and cover to keep warm.
Sauté Vegetables: In the same skillet, melt butter over medium-high heat. Add onions and mushrooms, cooking until onions are soft and mushrooms are golden brown (about 7-8 minutes). Reduce heat to low, add garlic, marjoram, and thyme, and stir for 1 minute. Remove the vegetable mixture from the skillet and cover to keep warm.
Cook the Noodles: While the vegetables are cooking, boil the egg noodles according to package instructions. Drain and set aside.
Prepare the Sauce: Add beef broth and Worcestershire sauce to the skillet. Scrape the bottom to deglaze and incorporate all the browned bits. Mix cornstarch with ¼ cup cold water and whisk it into the broth. Simmer while whisking until the sauce thickens.
Combine: Add the beef and vegetable mixture back into the skillet. Cook for 2-3 minutes until warmed through. Adjust seasoning with salt and pepper.
Serve: Serve the beef and sauce over the cooked noodles. Garnish with fresh parsley for a burst of color and flavor.
