01 - Evenly season beef short ribs with salt and black pepper on all sides.
02 - In a large skillet set over medium-high heat, brown short ribs on all sides for 2 to 3 minutes per side, then transfer to the slow cooker.
03 - Add onion, carrots, celery, and garlic to the same skillet. Sauté for 3 to 4 minutes until vegetables are slightly softened, then add to the slow cooker.
04 - Pour in beef broth and dry red wine. Stir in tomato paste and Worcestershire sauce until fully combined.
05 - Place thyme sprigs, rosemary sprigs, and bay leaves into the slow cooker.
06 - Cover and cook on LOW for 8 hours, or until ribs are extremely tender and meat falls off the bone.
07 - Remove and discard herb sprigs and bay leaves. Skim off any excess fat if needed.
08 - If desired, mix cornstarch with water and stir into the slow cooker. Cook on HIGH for 10 to 15 minutes until the sauce has thickened.
09 - Serve the beef short ribs hot with sauce and vegetables.