Prep the ingredients: Chop the onion and mince the garlic. If needed, cut the beef into bite-sized pieces.
Sear the beef (optional): Heat a skillet over medium-high heat, add a little oil, and brown the beef tips for 2–3 minutes per side for extra flavor.
Assemble in the crockpot: Add the beef, onion, and garlic to the slow cooker. Pour in the beef broth, soy sauce, Worcestershire sauce, thyme, and black pepper. Stir to combine.
Slow cook: Cover and cook on low for 6–8 hours or high for 3–4 hours until the beef is tender.
Thicken the sauce (optional): Mix 1 tablespoon cornstarch with 2 tablespoons water and stir it into the slow cooker. Let it cook for 15 minutes until thickened.
Cook the noodles: Boil the egg noodles according to the package instructions. Drain and set aside.
Serve and enjoy: Spoon the beef tips and gravy over the noodles. Garnish with parsley if desired.