Versatile beef stew

Name: Versatile beef stew
Ingredients: 900g braising steak (such as chuck or brisket), trimmed of large pieces of fat or gristle and cut into large chunks; 1 tbsp plain flour; 1-2 tbsp vegetable or sunflower oil; 2 onions, chopped; 2 celery sticks, chopped; 2 carrots, halved and cut into chunks; 2 bay leaves; 6 thyme sprigs, leaves picked; 150ml red wine (optional); 1 tbsp tomato purée; 2 tsp Worcestershire sauce; 1 beef stock cube or 600ml fresh strong beef stock; cooked green vegetables and mash, to serve (optional)