01 - Set the oven to 320°F.
02 - Pat steaks dry and season generously with salt and black pepper. Lightly dust with flour.
03 - Heat vegetable oil in a large ovenproof casserole over medium-high heat. Brown steaks for 2-3 minutes per side, then remove and set aside.
04 - In the same pan, add onions, carrots, celery, and garlic. Cook for 5 minutes until softened.
05 - Stir in tomato paste and cook for 1 minute to enhance flavor.
06 - Pour in red wine if using, scraping browned bits from the pan. Simmer for 2 minutes.
07 - Return steaks to the pan. Add beef stock, Worcestershire sauce, thyme, and bay leaves. Bring to a gentle simmer.
08 - Cover tightly and braise in the oven for 2 hours, turning steaks halfway through, until very tender.
09 - Remove thyme and bay leaves. Adjust seasoning with salt and pepper. Serve steaks with gravy and vegetables.