Finely shred 2 tablespoons peel from lemons. Squeeze juice to equal 3/4 cup. Set aside peel; cover and refrigerate juice.
In small saucepan heat milk over medium heat just until tiny bubbles begin to appear around the edge of the saucepan.
In large saucepan whisk sugar, salt, and lemon peel into egg yolks until well blended. Gradually whisk in warmed milk. Cook and stir continuously with a wooden spoon or heatproof rubber spatula over medium heat until mixture thickens and coats the back of a clean metal spoon, about 15 minutes (do not boil). Remove pan from heat. Transfer mixture to large bowl. Quickly cook by placing the bowl of custard in a very large bowl of ice water for about 5 to 7 minutes, stirring constantly. Once completely cool, stir in whipping cream. Cover and chill 4 to 24 hours.
Just before freezing stir in lemon juice. Strain through fine-mesh strainer; discard peel. Freeze in 4- or 5-quart ice cream freezer according to manufacturer's directions. If desired, ripen 4 hours