01 - Generously season short ribs with salt and black pepper on all sides.
02 - Heat a large skillet over medium-high heat. Sear short ribs on all sides, approximately 2 to 3 minutes per side, until browned. Transfer browned ribs to slow cooker.
03 - Add onion, carrots, celery, and garlic to the skillet. Sauté for 3 to 4 minutes until vegetables are slightly softened, then transfer to slow cooker.
04 - Pour beef broth and red wine over the contents in the slow cooker. Stir in tomato paste and Worcestershire sauce until fully combined.
05 - Add thyme sprigs, rosemary sprigs, and bay leaves to the slow cooker.
06 - Cover slow cooker and cook on LOW for 8 hours or until beef is tender and easily pulls away from the bone.
07 - Remove thyme, rosemary, and bay leaves. Skim surface fat as needed.
08 - For a thicker sauce, combine cornstarch with water and stir into the slow cooker. Cook on HIGH for 10 to 15 minutes until sauce is thickened.
09 - Plate braised short ribs with sauce and vegetables while hot.