Season the beef cubes with salt and pepper.
Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat.
Add the beef in batches and brown on all sides. Remove and set aside.
Add the onion to the same pot and cook until softened.
Stir in the garlic and cook for 30 seconds.
Add the tomato paste and cook for 1 minute, stirring constantly.
Pour in the beef broth and Worcestershire sauce, scraping up any browned bits from the bottom of the pot.
Return the beef to the pot.
Add the thyme and rosemary.
Bring the mixture to a gentle boil.
Reduce the heat to low, cover, and simmer for 1 hour.
Add the carrots, potatoes, and celery.
Cover and continue cooking for 45 to 60 minutes, or until the beef is fork-tender and the vegetables are cooked through.
In a small bowl, whisk together the flour and water until smooth.
Stir the slurry into the stew and cook for 5 minutes until slightly thickened.
Taste and adjust seasoning if needed.
Garnish with fresh parsley before serving.