This wonderfully refreshing soup started with some rich chicken stock and a few celery stalks. The sorrel on the allotment was still good in mid-November.

1 onion, peeled and chopped
Olive oil
1 medium potato, peeled and chopped
3 celery stalks, sliced
Chicken stock
Two large spoons Puy (or green) lentils
A handful of sorrel leaves
Salt and freshly ground black pepper

Pour a few tablespoons of olive oil into a saucepan on a medium heat and add the onion. Cook for about five minutes, stirring from time to time until the onion is soft but not coloured. Add the potato and celery and cook for a few minutes more. Add the Puy lentils, some chicken stock (about 500ml) and, when this is hot, add the sorrel leaves. Stir around and season. Cover and continue cooking on a lower heat.

When all the vegetables are soft, blitz the soup and then push it through a sieve. This is important to be sure that no strands of sorrel or celery remain. Return the soup to the saucepan, check the thickness of the soup and add more stock if necessary.

Serve very hot with crusty bread. A swirl of cream or soft cheese could be added but I am not convinced this is necessary.