Sauté the
onions in the butter in a large saucepan over medium
heat for 2-3 minutes, or until softened.
Add the
lettuce. Season with salt and pepper and add the
sugar. Pour in the water and simmer over low heat
for 30 minutes. Drain the lettuce, reserving the
stock.
Process 2 the
lettuce in a food processor or blender until 28
smooth.
Return the
lettuce puree to the saucepan over low heat. Add the
egg yolks and cream and mix well.
Stir constantly
for 5-10
minutes, or until
the mixture thickens, adding enough reserved stock
to make it smooth and creamy.
Ladle into soup
bowls and garnish with the parsley and Parmesan.
Serve hot.