In a large skillet over medium heat, cook the ground beef with the diced onion and minced garlic until the meat is browned and the onion is soft. Drain any excess fat.
Transfer the beef mixture to the slow cooker.
Add the chopped cabbage, uncooked rice, beef broth, tomato sauce, diced tomatoes, oregano, paprika, salt, and pepper.
Stir everything together until well combined.
Cover and cook on low for 6 to 8 hours or on high for 3 to 4 hours, until the cabbage is tender and the rice is fully cooked.