Heat the olive oil in a large pot over medium heat. Add the beef cubes and cook until browned on all sides, about 5 minutes.
Stir in the diced onion, carrots, and celery. Cook for 3 minutes until the onion softens.
Sprinkle the flour over the mixture and stir for 1 minute to coat everything evenly.
Add the tomato paste, dried thyme, salt, and pepper. Pour in the beef broth and stir well to combine.
Bring the stew to a gentle boil, then lower the heat to a simmer. Cover the pot and cook for 45 minutes.
Add the potato cubes and continue simmering uncovered for 20 more minutes until the potatoes are tender and the broth has thickened slightly.