Heat vegetable oil in a large heavy-bottomed Dutch oven over medium-high heat.
Sear beef cubes in batches until deeply browned on all sides, removing browned pieces to a side plate to avoid overcrowding the pan.
Add onion, garlic, carrots, and celery to the residual fat in the pot and sauté for 5 to 7 minutes until the onions are translucent and slightly softened.
Deglaze the pot by pouring in the beef stock and scraping the bottom with a wooden spoon to release the fond.
Return the beef and any accumulated juices to the pot; add Worcestershire sauce, thyme, salt, and pepper.
Bring the liquid to a rolling boil, then immediately reduce heat to low, cover, and simmer for 90 minutes or until the beef reaches fork-tender consistency.
Increase heat to medium-low and stir in the dried egg noodles.
Cook the noodles uncovered for 8 to 10 minutes, stirring occasionally to prevent sticking.
In a small bowl, whisk together the flour and cold water until a smooth slurry forms.
Slowly stir the slurry into the stew and simmer for an additional 3 minutes until the broth has thickened into a gravy-like consistency.
Adjust seasoning with salt and pepper to taste before serving.