01 - Pat short ribs dry and season all sides evenly with salt and pepper.
02 - Heat a large skillet over medium-high heat. Brown short ribs on all sides, about 2 to 3 minutes each side. Transfer browned ribs to the slow cooker.
03 - Add chopped onion, carrots, celery, and minced garlic to the hot skillet. Sauté for 3 to 4 minutes until slightly softened, scraping up any browned bits. Transfer vegetables to the slow cooker.
04 - Pour beef broth and dry red wine into the slow cooker. Stir in tomato paste and Worcestershire sauce until combined.
05 - Nestle fresh thyme, rosemary sprigs, and bay leaves among the beef and vegetables in the slow cooker.
06 - Cover and cook on LOW for 8 hours, until short ribs are fork-tender and meat pulls easily from the bone.
07 - Remove and discard herb sprigs and bay leaves. Skim excess fat from the sauce, if desired.
08 - If a thicker sauce is preferred, mix cornstarch with water and stir into the slow cooker. Cover and cook on HIGH for 10 to 15 minutes, until sauce thickens.
09 - Serve beef short ribs hot, spooning sauce and vegetables over top.