Soffritto, also called a mirepoix, is a classic base of finely chopped onion, carrot and celery that is the starting point of so many recipes. These days, you don't need superb knife skills as you can buy it pre-chopped from the supermarket.
Heat the oil in a deep saucepan and gently fry the soffritto or vegetable mix for 5 minutes over a medium heat until softened. Add the passata and vegetable stock to the pan and bring to a steady simmer.
Add the haddock and beans, cover and simmer for 4 to 5 minutes until the fish is cooked through and starting to break into chunks. Scatter with basil leaves and serve.