- Toss the diced beef in plain flour, salt, and pepper. 
- Heat vegetable oil in a large pot over medium heat. Brown the beef in batches, ensuring each piece is well-seared. Remove and set aside. 
- In the same pot, add the onion and garlic, cooking until softened. 
- Add the carrots, celery, and mushrooms, and cook for an additional 5 minutes. 
- Return the beef to the pot and stir in the beef stock, tomato puree, Worcestershire sauce, and dried thyme. Season with salt and pepper. 
- Bring to a boil, then reduce the heat and let it simmer gently for about 1.5 hours, or until the beef is tender and the sauce has thickened.