In a large Dutch oven or heavy pot, heat oil over high. Add beef, season with salt and pepper, and cook until seared and brown, about 6 minutes. Add onion and season with salt and pepper. Cook until onion begins to soften (reducing heat if necessary), about 5 minutes. Stir in flour until beef and onion are coated and cook 1 to 2 minutes (do not burn). Add broth and 3 cups water, stirring and scraping up browned bits. Bring to a boil; reduce to a simmer and cook until beef is tender, about 25 minutes.
Add carrots and potatoes and cook until potatoes are tender, about 10 minutes. Add noodles and cook until tender, about 8 minutes. Season with salt and pepper. To serve, stir in parsley and vinegar.
Cutting vegetables into evenly sized cubes helps to ensure that they'll finish cooking at the same time.