Meanwhile, prepare the chard. Cut the stalk away from the green lead and thinly slice. Add these bits to the veg pot and thinly slice the green leafy part, keeping it aside for the moment.
When the vegetables are soft, add the beans, stir to coat and pour in the veg stock. Bring to the boil and simmer for 15-20 minutes until the potatoes are soft.
Make the pisto, by blending together all the ingredients.
Blend the soup, then stir in the sliced green chard leaves and allow to simmer for just a couple of minutes. Finally, add the pistou and check the seasoning.
Leave to sit for 5 mins with the lid on before serving.