01 - Generously season beef short ribs with salt and black pepper on all sides.
02 - Heat a large skillet over medium-high heat. Brown the short ribs on all sides, about 2 to 3 minutes per side. Transfer seared ribs to slow cooker.
03 - Add onion, carrots, celery, and garlic to the skillet. Sauté for 3 to 4 minutes until vegetables begin to soften. Add mixture to slow cooker.
04 - Pour beef broth and red wine into slow cooker. Stir in tomato paste and Worcestershire sauce until fully blended.
05 - Nestle thyme sprigs, rosemary sprigs, and bay leaves among the ingredients in the slow cooker.
06 - Cover and cook on LOW for 8 hours, or until short ribs are extremely tender and meat easily separates from the bone.
07 - Discard bay leaves, thyme, and rosemary sprigs. Skim off any excess surface fat from sauce if visible.
08 - For a thicker sauce, combine cornstarch with cold water, then stir the mixture into the slow cooker. Switch to HIGH and cook for 10 to 15 minutes until sauce is glossy and thickened.
09 - Serve beef short ribs hot with vegetables and sauce spooned over top.