01 - Generously season all sides of beef short ribs with salt and black pepper.
02 - Heat a large skillet over medium-high. Sear short ribs 2–3 minutes per side until deeply browned. Transfer to the slow cooker.
03 - Add onion, carrots, celery, and garlic to the same skillet. Sauté 3–4 minutes until slightly softened, then transfer to slow cooker.
04 - Pour in beef broth and red wine. Stir in tomato paste and Worcestershire sauce.
05 - Place thyme, rosemary, and bay leaves into the slow cooker.
06 - Cover and cook on LOW setting for 8 hours, or until meat is tender and pulls easily from the bone.
07 - Discard herb sprigs and bay leaves. Skim excess fat from the surface if necessary.
08 - If a thicker sauce is desired, stir in cornstarch slurry and cook on HIGH for 10–15 minutes until sauce thickens.
09 - Arrange short ribs and vegetables on plates. Spoon sauce over and serve hot.