01 - Pat the beef cubes dry with paper towels and season thoroughly with salt and pepper.
02 - Place seasoned beef, carrots, parsnips, potatoes, onion, and celery in the slow cooker.
03 - In a small bowl, whisk together tomato paste, garlic, thyme, rosemary, bay leaves, Worcestershire sauce, and beef broth until well combined.
04 - Pour the liquid mixture over the meat and vegetables. Gently stir to distribute evenly.
05 - Cover and cook on low setting for 8 hours, or until beef is fork-tender and vegetables are fully cooked.
06 - During the final 30 minutes of cooking, mix cornstarch with cold water to create a smooth slurry. Stir into the stew and continue cooking until thickened.
07 - Remove and discard bay leaves. Taste and adjust seasoning with additional salt and pepper if desired before serving.