There's something so incredibly humble about onion soup. It's absolutely one of my favourites but unfortunately I only ever get to make it in the restaurant or for myself as the missus thinks she's allergic to onions. (She's not, because I whiz them up into loads of dishes without her knowing!)If you have the opportunity, get hold of as many different types of onion for this soup as you can – you need about 1kg in total. Sweat them gently and you'll be amazed at all the flavours going on.