Lime or Lemon Chiboust

Procedure

1. Heat the juice, zest, and sugar to a simmer.
2. Whip the egg yolks with the second quantity of sugar and the cornstarch. As when making pastry cream, gradually stir the juice into the egg yolk mixture, then return to the saucepan and bring to a boil. Remove from the heat.
3. Soak the gelatin</