Ingredients:
1 teaspoon extra virgin olive oil
1 bunch spring onions or 1 leek, chopped
1 medium, diced
1 liter water or stock
3 bunches watercress
75 ml sour cream
pinch of ground nutmeg
black pepper
salt

Directions:
In a large saucepan, heat the oil. Add the spring onions or leek and cook over a low heat until tender, for about 10 minutes.
Add the potatoes and the water or stock. Bring to a boil; reduce the heat and simmer, covered for 10minutes.
Wash, drain and roughly chop the watercress. Add it to the pan and return to a boil for 2 minutes. Turn off the heat and leave to stand for 5 minutes.
In a blender or food processor, liquidize the soup and return it to the pan. Stir in the sour cream. Add the nutmeg and season to taste.