01 - Sprinkle short ribs evenly with salt and black pepper on all sides.
02 - Heat a large skillet over medium-high heat. Sear the short ribs for 2–3 minutes per side until deeply browned. Transfer browned ribs to the slow cooker.
03 - Add chopped onion, carrots, celery, and minced garlic to the same skillet. Sauté for 3–4 minutes until vegetables begin to soften. Transfer vegetables to the slow cooker.
04 - Pour beef broth and red wine over the ribs and vegetables in the slow cooker. Stir in tomato paste and Worcestershire sauce until well blended.
05 - Nestle the thyme sprigs, rosemary sprigs, and bay leaves into the slow cooker mixture.
06 - Cover and cook on LOW for 8 hours until the ribs are extremely tender and easily separate from the bone.
07 - Remove thyme sprigs, rosemary sprigs, and bay leaves. Skim excess fat from the sauce if desired.
08 - Whisk cornstarch with water, then stir the slurry into the slow cooker. Cover and cook on HIGH for 10–15 minutes or until the sauce thickens.
09 - Present the short ribs hot, topped with the sauce and vegetables.