<ol>
<li>Prepare the vegetables by peeling and chopping the potatoes
finely chopping the onions
leeks and garlic.</li>
<li>Heat a little oil in a pan and add the chopped vegetables
gently cooking them for about 5 minutes.</li>
<li>Add the vegetable stock to the same pan and turn up the heat until simmering
adding the watercress after about 10 minutes. Cook until all the vegetables are soft and easily mashed.</li>
<li>Liquidize the soup either with a hand blender or in a mixer
until smooth.</li>
<li>If the soup has cooled too much whilst being liquidized
stir in the crème fraîche and reheat before serving (otherwise serve straight away). Season to taste.</li>
</ol>