01 - Generously season beef short ribs with salt and black pepper on all sides.
02 - In a large skillet over medium-high heat, brown short ribs on all sides for 2 to 3 minutes per side, then transfer to slow cooker.
03 - Add chopped onion, carrots, celery, and minced garlic to the skillet. Sauté for 3 to 4 minutes until 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 combined.
05 - Nestle fresh thyme sprigs, rosemary sprigs, and bay leaves among the ingredients in the slow cooker.
06 - Cover and cook on low setting for 8 hours, until meat is extremely tender and separates easily from the bone.
07 - Remove thyme, rosemary, and bay leaves. Skim any excess fat from the surface of the sauce as needed.
08 - For a thicker sauce, mix cornstarch with cold water and stir into the slow cooker. Cook on high for an additional 10 to 15 minutes until thickened.
09 - Ladle beef short ribs with sauce and vegetables onto plates and serve hot.