Mix the egg yolks with sugar, cornstarch, lemon juice and zest in a saucepan. Add the white wine and heat over medium heat for 10 to 15 minutes. Keep beating with the whisk or, even better, with the electric whisk, until a thick, foamy mass is formed. The mixture must not boil, otherwise the egg yolk will curdle.
Let the soup cool down and fold in the egg whites just before serving.
Again a classic from my childhood. We have wake-up cuts or poor knights and compotes.