Pat the beef cubes dry and place them in a large bowl. Add the flour, 1 teaspoon of salt, and 1/2 teaspoon of black pepper. Toss until the beef is evenly coated.
Heat the olive oil in a large Dutch oven over medium-high heat. Working in batches, add the beef in a single layer and sear until well-browned on all sides, about 5-7 minutes per batch. Transfer the browned beef to a separate plate.
Reduce the heat to medium. Add the onion, carrots, and celery to the pot. Cook, stirring occasionally, until softened, about 6-8 minutes.
Stir in the minced garlic and tomato paste. Cook for 1 minute more, until fragrant.
Pour in the red wine, scraping the bottom of the pot with a wooden spoon to release any browned bits. Let it bubble and reduce by about half, which should take 2-3 minutes.
Return the seared beef and any accumulated juices to the pot. Add the beef broth, Worcestershire sauce, dried thyme, and the bay leaf. Stir to combine.
Bring the stew to a boil, then reduce the heat to low. Cover the Dutch oven and let it simmer gently for 1.5 hours.
Stir in the potatoes. Cover and continue to simmer for another 45-60 minutes, or until the beef is very tender and the potatoes are cooked through.
Remove the bay leaf. Taste the stew and season with additional salt and pepper as needed before serving.