A meltingly tender one-pot beef casserole

Name: A meltingly tender one-pot beef casserole
Prep time: 10 min
Cook time: 2 h 15 min
Total time: 2 h 25 min
Cuisine: American
Ingredients: 1 kg chuck or boneless shin/gravy beef; 1 medium onion, diced; 2 small celery stalks, sliced; 2 small carrots, finely diced; 1 tbsp plain flour; 3 cups beef stock; ¼ cup tomato paste; 3 large potatoes, peeled, cut into large dice; 1-2 bay leaves (fresh or dried); 4 sprigs fresh thyme or small sprigs of rosemary or parsley