01 - Season the beef cubes evenly with salt and black pepper.
02 - In a large skillet over medium-high heat, brown the 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 - Whisk together beef broth, red wine if using, tomato paste, and Worcestershire sauce in a bowl; pour over the meat and vegetables.
05 - Add bay leaves, dried thyme, and dried rosemary; stir gently to combine all ingredients.
06 - Cover and cook on low heat for 8 hours, or high heat for 4 to 5 hours, until beef is tender and vegetables are cooked through.
07 - Thirty minutes before serving, mix cornstarch with cold water to create a slurry; stir into the stew, cover, and cook on high for 30 minutes until thickened.
08 - Remove bay leaves and adjust seasoning as needed before serving.