Step 1: 1) Make sure you wash all the vegetables really well, especially the leeks as they can hold a lot of dirt in their leaves. Cut celery and leeks into large chunks and dice the onion.
Step 2: 2) Place the celery, leeks and onion into large pan with the stock and bring to the boil. Add the seasoning and herbs and leave to simmer away for around 20 minutes.
Step 3: 3) Turn off the heat and blend to the consistency you wish. I prefer mine slightly chunky as makes it seem a more filling meal! Remember to check the seasoning before you serve.