Place the beans in cold water and soak for 12 hours, then rinse under running water. Clean the leek and slice one into rings and the other into diagonals; peel the potato and chop it into bits.Heat 2 spoonfuls of oil in a pan, add the leek and fry until soft, add the potato and brown it lightly, add the beans and cover with plenty of water. Bring to the boil, cover the pan and simmer for over an hour, until the beans are soft.Steam the leek diagonals and keep aside. Sieve the leek in a vegetable mill and set aside. Do the same with the beans, keeping a spoonful of whole beans. Put the pure in a pan, add the whole beans, and if necessary, a bit of water. It must reach a creamy consistency.Then rinse the fish fillets, chop them into chunks and brown them in a pan with a dash of oil, then season with salt and pepper. In the meanwhile cook the pasta in plenty of boiling salted water, mix it with the bean cream and serve it, arranging a cod fillet and a leek diagonal on each dish. Sprinkle with raw oil and a grind of pepper and serve.