Heat olive oil in a large pot over medium heat. Add diced onion and minced garlic; cook until they soften, about 3 minutes.
Add ground beef and cook, stirring to break up clumps, until the meat is browned, about 7 minutes. Season with salt and pepper.
Stir in diced tomatoes, shredded cabbage, and dried thyme. Pour in the chicken broth, bring to a boil, then reduce heat and simmer for 25 minutes until the cabbage is tender.
Ladle into bowls and garnish with a sprinkle of fresh parsley if desired.