Brown the Beef:
Pat beef dry with paper towels and season generously with salt and pepper.
Heat 2 tbsp oil in a large Dutch oven or heavy pot over medium-high heat.
Brown beef in batches (do not overcrowd) for about 4–5 minutes per batch. Remove and set aside.
Sauté Vegetables:
Add remaining 1 tbsp oil to the pot.
Add onions and cook until softened, about 5 minutes.
Stir in garlic and cook for 1 minute.
Make the Base:
Sprinkle flour over vegetables and stir for 1–2 minutes to cook out the raw taste.
Stir in tomato paste, then slowly pour in wine (if using), scraping up browned bits.
Add beef broth, thyme, rosemary, and bay leaves.
Simmer the Stew:
Return beef to the pot.
Bring to a boil, then reduce heat to low. Cover and simmer for 1 ½ to 2 hours, stirring occasionally, until beef is fork-tender.
Add Vegetables:
Add carrots, potatoes, and celery.
Simmer uncovered for another 30–40 minutes until vegetables are tender and stew has thickened.
Finish and Serve:
Remove bay leaves.
Adjust seasoning with salt and pepper.
Garnish with fresh parsley and serve hot.