Soups are my winter staple. I always like to have a pot on the go. I invented this one when I had a surplus of leeks and the landcress at the allotment was in danger of being caught by the frost.  It has now become one of my firm favourites.  

1. Bring the stock to the boil and cook the potatoes for a few minutes before adding the leeks and simmering until both are cooked.
2. Add the watercress and frozen peas, bring to the boil and simmer for two minutes or until the watercress is soft.
3. Process the soup until smooth and creamy and season to taste with salt and pepper.
4. Serve sprinkled with watercress leaves.