01 - Pat beef cubes dry using paper towels and season evenly with salt and black pepper.
02 - Heat a large skillet over medium-high heat and brown beef cubes in batches on all sides for enhanced flavor, then transfer to the slow cooker.
03 - Layer carrots, potatoes, celery, onion, and garlic over the seared beef in the slow cooker.
04 - In a separate bowl, whisk together beef broth, tomato paste, Worcestershire sauce, red wine (if using), dried thyme, and rosemary. Pour the mixture over the beef and vegetables. Add bay leaves.
05 - Cover and cook on LOW for 8 hours or HIGH for 4 to 5 hours until beef and vegetables are tender.
06 - Stir cornstarch and cold water together until smooth, then incorporate into the stew. Cover and cook on HIGH for an additional 15 to 20 minutes until thickened.
07 - Remove bay leaves, taste the stew, and adjust seasoning if necessary.
08 - Sprinkle chopped fresh parsley on top before serving, if desired.