First, pat the beef cubes dry with paper towels. Season them with salt and pepper, then sprinkle with the flour and toss gently to coat each piece evenly. Heat the vegetable oil in a large heavy-bottomed pot or Dutch oven over medium-high heat. Brown the beef cubes in batches, turning them to get a nice sear on all sides. This should take about 3-4 minutes per batch. When browned, transfer the beef to a plate and set aside.

In the same pot with the browned beef bits, add the diced onion. Sauté for about 5 minutes until the onion softens. Then add the minced garlic and cook for another minute, stirring so the garlic doesn’t burn.

Stir in the tomato paste and cook for 2 minutes to deepen its flavor. Next, pour in the red wine (if using) to deglaze the pot, scraping up all the tasty browned bits from the bottom. Let it simmer for 2-3 minutes to reduce slightly.

Return the browned beef to the pot. Add the beef broth, dried thyme, rosemary, and bay leaves. Stir everything together, then bring the stew to a boil. Once boiling, reduce the heat to low, cover the pot, and let it simmer gently for about 1.5 hours, or until the beef becomes tender.

Add the carrots, potatoes, and celery to the pot. Continue simmering, covered, for another 30 to 40 minutes until the vegetables are tender but still hold their shape.

Remove the bay leaves from the stew. Taste and adjust seasoning with salt and freshly ground black pepper, if needed. Ladle the warm stew into bowls, and sprinkle with chopped fresh parsley to brighten the dish. Enjoy your homemade beef stew with crusty bread or over creamy mashed potatoes for a truly comforting meal!