01 - Rub beef cubes with kosher salt, black pepper, and dried thyme, ensuring even coating on all sides.
02 - Transfer seasoned beef to the slow cooker insert. Top with chopped onion and minced garlic, distributing evenly.
03 - Whisk together beef broth, Worcestershire sauce, tomato paste, and flour or cornstarch in a medium bowl until completely smooth and lump-free.
04 - Pour the liquid mixture over the beef and vegetables in the slow cooker. Stir gently to distribute ingredients evenly.
05 - Cover and cook on low setting for 6–7 hours or on high for 3–4 hours, until beef is fork-tender and gravy has thickened.
06 - Taste the gravy and adjust salt and pepper if necessary. Serve hot over mashed potatoes, noodles, or rice. Garnish with chopped fresh parsley.