1. Roughly chop the leek into chunks and place into a pan along with vegetable stock.

2. Quickly dice the onion and add to the leeks. Trim the fennel and slice, again, add these to the leek and the onion. Crush the garlic and add to the pan along with a little salt and pepper.

3. Put the pan on a low heat and cook until the leeks and onion are nice and soft, about 30 minutes.

4. Transfer the contents of the pan to a blender, blend until smooth. Serve topped with a sprinkle of fennel seeds if desired.