Combine cornstarch, sugar and salt in saucepan; gradually add water, stirring until smooth. Bring to a boil over medium heat, stirring, and boil 1 minute.
Remove from heat and quickly add one half the hot mixture to the egg yolks, mixing well. Return to the hot mixture, blending thoroughly.
Bring the mixture to a boil, stirring, over medium heat. Boil 1