Put leaves of watercress into a small pan of boiling water. Refresh under cold water.

Heat the oil in a pan

Add peeled an washed sliced onions an leek, cook for a few minutes.

Add the stock, the peeled, washed and sliced potatoes and the rest of watercress and season.

Simmer for 30minutes

Pass the soup firmly through a sieve then pass through a conical strainer

Return to a clean pan, recoil, correct the seasoning and consistency

Garnish with watercress

Serve with fried croutons separately