Heat olive oil in a large pot over medium heat. Add ground beef and cook until browned, about 3-5 minutes, breaking it apart as it cooks; drain any excess fat.

Add diced onion and bell peppers to the pot. Cook, stirring occasionally, until vegetables are tender, about 3-4 minutes.

Mix in minced garlic, Italian seasoning, and red pepper flakes, cooking until fragrant, roughly 1 minute.

Pour in the diced tomatoes with their juice, tomato sauce, and beef broth. Return the browned ground beef to the pot. Season with salt and black pepper to taste. Bring the mixture to a boil, then lower the heat and let it simmer until flavors meld, about 15-20 minutes.

Stir in the cooked rice and chopped parsley, and continue to cook until everything is heated through, approximately 1-2 minutes.

Ladle the soup into bowls and serve warm.