I love soup. Warming, nourishing, easy to make and very useful for using up bits and bobs in your fridge, it’s a very useful addition to any cook’s repetoire. Some soups are just a delicious dinner and rarely thought of again, but some are classics that end up defining a nation and becoming famous outside their home. Vichyoisse, gazpacho, tom yum, minestrone, we all know and love them. But one that deserves to be on that roll call is the Portuguese staple caldo verde or ‘green broth’.