There are no recipes for watercress prior to Victorian industrialization, because wild watercress carries the danger of liver fluke (a small flea) unless it is picked in running water. At the time of the Industrial Revolution, specially designed watercress beds, with a stream of water running through, were set up, and quite sizeable areas given over to growing what was the newest food fad of the day.
For the mousse, mix together the ricotta, egg yolk, and sugar, beating well. Add the lemon zest and juice, and then the minced watercress. Stir in the gelatin and season with salt and pepper. Whisk the egg whites until they are stiff, and fold in. Chill until the mousse is just set.
Brush the bread with olive oil and toast it under a preheated hot broiler or in a hot oven until it is golden brown.
Mash together the anchovies and garlic into a fine paste. Season with pepper. Spread this on the hot crostini, and serve with the watercress mousse on top.
© 1999 Jennifer Paterson and Clarissa Dickson Wright estate. All rights reserved.