01 - Generously season beef short ribs with salt and black pepper on all sides.
02 - Heat olive oil in a large skillet over medium-high heat. Sear short ribs on all sides until well-browned, about 2 to 3 minutes per side. Transfer browned ribs to slow cooker.
03 - In the same skillet, sauté onion, carrots, and celery for 3 to 4 minutes until softened. Add minced garlic and cook for an additional minute.
04 - Add tomato paste to vegetables in the skillet, stirring and cooking for 1 minute. Pour in red wine or additional beef broth, scraping up browned bits from the pan.
05 - Transfer vegetables and sauce to the slow cooker. Add beef broth, Worcestershire sauce, thyme, rosemary, and bay leaves.
06 - Cover and cook on low for 7 hours or on high for 4 to 5 hours, until the short ribs are tender and falling off the bone.
07 - Remove bay leaves and herb stems. Skim excess fat from the sauce if desired. Serve short ribs with vegetables and sauce over mashed potatoes, polenta, or egg noodles.