Bring a large pot of salted water to a boil. Add egg noodles and cook according to package instructions until al dente, about 7-8 minutes. Drain and set aside.
Season the beef tips with salt and black pepper.
Heat olive oil in a large skillet over medium-high heat. Add beef tips in a single layer and sear until browned on all sides, about 4-5 minutes. Remove beef from skillet and set aside.
In the same skillet, reduce heat to medium. Add diced onion and cook until softened, about 4 minutes.
Add minced garlic and cook for 1 minute until fragrant.
Sprinkle flour over the onions and garlic, stirring constantly for 1-2 minutes to cook the flour and form a roux.
Gradually whisk in beef broth, scraping the bottom of the skillet to deglaze and dissolve any browned bits.
Add Worcestershire sauce, Dijon mustard, and dried thyme. Stir to combine.
Return the beef tips to the skillet. Reduce heat to low, cover, and simmer for 10-12 minutes until beef is tender and sauce has thickened.
Remove skillet from heat and stir in sour cream and unsalted butter until smooth and creamy. Adjust seasoning with additional salt and pepper if needed.
Add cooked egg noodles to the skillet and gently toss to coat noodles with the beef and gravy.
Sprinkle chopped fresh parsley over the top before serving.