Preheat the oven to 180 degrees Celsius.
Peel and finely dice the shallot. Cut the leek in half lengthways and then finely slice. Wash and pick the watercress and basil leaves, reserving the stalks. Peel and dice the potato.
Heat a pan, add olive oil and sweat the leek and shallot with a pinch of salt. Once transparent, add the watercress stalks and the potato. Deglaze with the white wine and reduce to a third. Add the chicken stock, bring to the boil and cook until the potato is soft. Add the chives and the basil and watercress leaves and cook for 30 seconds. Transfer to a food processor and puree. Season to taste.
For the parmesan tuiles: grate the parmesan cheese. Using a stainless steel ring, lay out individual circles of parmesan about 2mm thick. Leave a 3cm gap between each circle. Remove the rings, transfer to the oven and bake for 5 minutes until golden brown. Remove from the oven and whilst the tuiles are still warm, curve them over a rolling pin. They will go crispy as they cool.
Serve the soup with a parmesan tuile.
«Replace some of the watercress with a little rocket or spinach to give a different flavour to your soup.»
A seasonal treat - fresh watercress soup served with crisp parmesan tuiles.