By Barbara Kafka
This beautiful green soup with a peppery punch is elegant and should be silky smooth—no food processor, please. This is a good dinner party starter.
In a medium saucepan, bring the watercress, stock, and salt to a boil. Lower the heat and simmer, stirring occasionally with a wooden spoon, for 13 to 15 minutes, or until the stems are soft.
In a blender, working in batches of no larger than 2 cups (500