Season the beef cubes with salt and pepper. Lightly dust them with flour, shaking off the excess.
Sear the Beef
Heat olive oil in a pot over medium-high heat. Sear the beef in batches until browned on all sides. Remove and set aside.
Build the Base
Lower the heat to medium and sauté the onion until soft and translucent. Add the garlic and cook until fragrant, about 1 minute. Stir in the tomato paste and cook for another minute.
Deglaze the Pot
Pour in the red wine (if using) and scrape up any browned bits from the bottom. Let it simmer for 2 minutes.
Combine Ingredients
Return the beef to the pot and add the beef broth, carrots, celery, potatoes, bay leaves, thyme, and rosemary. Bring to a boil.
Simmer
Lower the heat, cover, and let it simmer gently for 2 – 2.5 hours, stirring occasionally, until the beef is tender and the stew is flavorful.
Thicken (Optional)
If you prefer a thicker stew, stir in the cornstarch slurry and let it simmer for an additional 5 minutes.
Serve
Remove the bay leaves and adjust seasoning with salt and pepper. Serve hot with crusty bread or over a bed of mashed potatoes.