Bring the milk, all but 1/2 cup, to a boil in a stainless steel saucepan (do not use an aluminum container), adding the grated lemon rind and a pinch of salt. Remove from the fire.
Whip the egg yolks with the sugar in a bowl. Add the cold 1/2 cup of milk, and then add the hot milk a little at a time. Put the mixture in a pot on the fire and cook over very low heat for 20 mins, stirring constantly. Do not allow to boil. When the mixture starts thickening, pour it into a bowl and cool, stirring frequently. Strain through a fine sieve.
Once entirely cooled, put the mixture in an ice-cream machine and churn until it reaches the proper consistency. Place in an ice-cream freezer.
Note:
Churning time varies depending on the ice-cream machine used. An ice-cream freezer holds a temperature just below freezing.
