Dice the red peppers, carrot, and onion into small cubes. Finely chop the garlic.
Heat the olive oil in a large pot over medium heat. Add the onion, red peppers, and carrot, and sauté gently for about 5 minutes.
Stir in the garlic, oregano, tomato purée and chilli flakes. Cook for a minute, then add the chopped tomato and enough water to cover the vegetables generously.
Add the bay leaf and vegetable stock cube. Bring to a boil, then reduce the heat and simmer for 20–25 minutes, or until the vegetables are tender.
Turn off the heat and add the parsley. Using a hand-held blender, purée the soup to your desired texture- smooth or rustic.
Stir in the drained butter beans and chopped kale. Return to the heat and cook for about 5 minutes, or until the kale is tender.
Ladle the soup into bowls and serve hot with crusty bread or pitta.