Brown the beef
In a large skillet over medium heat, cook the ground beef and diced onion, breaking up the meat, until the beef is no longer pink and the onion is soft, about 6–8 minutes. Drain excess fat if needed.Add the garlic
Stir in the minced garlic and cook for 30–60 seconds until fragrant. (If using garlic powder, add it later with the seasonings.)Layer the slow cooker
Add the chopped cabbage and diced carrot to the bottom of a 5–6 quart slow cooker. Spoon the beef and onion mixture over the top.Add liquids and tomatoes
Pour in the diced tomatoes with their juices, tomato sauce, and beef broth. Stir gently to combine.Season the soup
Add the uncooked rice, Worcestershire sauce, thyme, oregano, paprika, salt, pepper, brown sugar (if using), garlic powder (if not using fresh), and bay leaf. Stir so everything is evenly distributed.Cook
Cover and cook on LOW for 6–8 hours or on HIGH for 3–4 hours, until the cabbage is tender and the rice is cooked. Stir once or twice if possible, especially toward the end.Adjust and serve
Remove the bay leaf. If the soup is thicker than you prefer, add a little more broth or water. Taste and adjust seasoning. Serve hot with parsley and sour cream, if desired.
