One spring day, I was at Paul Levy’s house outside of Oxford. He and his Aga were making a wonderful soup base from his wintered-over leeks and plentiful supply of asparagus. I promptly stole the notion and made this soup with it. The vegetarian Asparagus Stock base is best made ahead, as it takes quite a long time. I make this base after I have cooked a lot of asparagus for a feast. It can be use