Pour the tomatoes into a large pan and add a can of cold water. Season with salt and pepper and bring to the boil, then reduce the heat to a simmer.
Roughly shred the cabbage leaves and add them to the pan. Partially cover the pan and simmer gently for about 15 minutes or until the cabbage is tender.
Drain and rinse the cannellini beans, add to the pan and warm through for a few minutes. Check and adjust the seasoning, then ladle the soup into bowls and drizzle each one with a little olive oil and serve.