01 - Generously season beef short ribs on all sides with salt and ground black pepper.
02 - Heat a large skillet over medium-high. Sear short ribs on each side for 2 to 3 minutes until browned, then transfer to the slow cooker.
03 - Add chopped onion, sliced carrots, sliced celery, and minced garlic to the skillet. Sauté for 3 to 4 minutes until aromatic and slightly softened, then transfer to the slow cooker.
04 - Pour beef broth and dry red wine into the slow cooker. Stir in tomato paste and Worcestershire sauce until fully incorporated.
05 - Nestle in thyme sprigs, rosemary sprigs, and bay leaves among the ribs and vegetables.
06 - Cover and cook on LOW for 8 hours, until beef is exceptionally tender and falling off the bone.
07 - Remove herb sprigs and bay leaves. Skim off any excess fat from the cooking liquid if needed.
08 - For a thicker sauce, mix cornstarch with water and stir into the slow cooker. Switch to HIGH and cook for 10 to 15 minutes until sauce thickens.
09 - Serve hot short ribs with vegetables and spoon sauce over the top.