Place roast and vegetables in slow cooker.
Mix stock, vinegar, Worcestershire sauce, spices and salt in small bowl. Pour over meat and vegetables in slow cooker. Cover. Cook 4 hours on HIGH or 8 hours on LOW.
Remove roast and vegetables to serving platter. Keep warm.
Whisk water and cornstarch in small bowl until well blended. Stir cornstarch mixture into liquid in slow cooker. Cover and cook an additional 30 minutes on HIGH or until sauce is slightly thickened. Stir sauce before serving.