01 - Evenly season the beef short ribs with salt and black pepper on all sides.
02 - Heat a large skillet over medium-high. Sear the short ribs for 2 to 3 minutes per side until deeply browned. Transfer ribs to the slow cooker.
03 - Place onions, carrots, celery, and garlic into the same skillet. Sauté for 3 to 4 minutes until lightly softened, then add to the slow cooker.
04 - Pour beef broth and red wine into the slow cooker. Stir in tomato paste and Worcestershire sauce until combined.
05 - Add thyme, rosemary, and bay leaves to the slow cooker.
06 - Cover and cook on LOW setting for 8 hours, until ribs are extremely tender and meat is falling off the bone.
07 - Remove thyme, rosemary, and bay leaves. Skim excess fat from the cooking liquid as needed.
08 - To thicken, mix cornstarch with water and stir into the slow cooker. Cook on HIGH for 10 to 15 minutes until sauce slightly thickens.
09 - Plate the beef short ribs with sauce and vegetables. Serve hot.