Brown the ground beef and onion in a large skillet over medium heat for 5-7 minutes until the beef is browned and the onion is soft. Drain excess fat and transfer the mixture to the slow cooker.

Add the diced bell peppers and uncooked rice to the crock pot, mixing gently to combine.

Pour in the diced tomatoes and beef broth, then sprinkle with Italian seasoning, salt, and pepper. Stir well to combine all ingredients.

Cover the crock pot and cook on low for 6-8 hours or on high for 3-4 hours.

Once cooking time is complete, stir the soup and ladle into bowls, adding optional toppings if desired.