Scald milk in a double boiler or heavy saucepan. (Scald by simmering the milk over medium heat until the milk reaches approximately 175 degree F. Then remove from the heat.)
Combine sugar, salt, and egg yolks in a separate bowl and whip them together with a wire whisk or a hand mixer until the mixture thickens enough to leave a trailing on the surface, approximately 3 minutes.
Gradually add the scalded milk to the thickened egg mixture.
Beat on low or whisk while slowly pouring in 3/4 to 1 cup of milk at a time.
Do not over beat; beat just until the milk is evenly mixed into the egg mixture.
Once all the milk has been added into the egg mixture, pour the combined ingredients back into the double boiler or saucepan.
Cook over medium-low heat until the mixture almost reaches boiling point, approximately 180 degree F.
Stir constantly and do not allow mixture to boil (boiling may cause it to curdle).
When the custard has thickened properly, remove it from the heat and allow it to cool before placing it in the refrigerator to chill.
Pour the custard into a glass bowl and cover the surface with plastic wrap to prevent a film from forming on the surface.
After the custard has cooled, place it in the refrigerator for at least 4 hours and serve.