01 - Season beef cubes evenly with salt and black pepper.
02 - In a large skillet over medium-high heat, brown beef in batches to enhance flavor, then transfer to the slow cooker.
03 - Place carrots, parsnips, potatoes, onion, celery, and garlic into the slow cooker with the beef.
04 - In a bowl, whisk beef broth, red wine (if using), tomato paste, and Worcestershire sauce; pour evenly over meat and vegetables.
05 - Incorporate bay leaves, thyme, and rosemary, stirring gently to combine ingredients.
06 - Cover and cook on low for 8 hours or on high for 4–5 hours, until beef and vegetables are tender.
07 - Thirty minutes before serving, create a slurry by mixing cornstarch with cold water; stir into the stew, then cook on high for 30 minutes until thickened.
08 - Remove bay leaves, adjust seasoning to taste, and serve.