* leaves are measured by "hardpacking:" press down in the measuring cup with your fingers

In a heavy 2-quart saucepan or double boiler over medium-low heat, stir and heat the cream, milk, and sugar until the sugar dissolves. Do not boil.

In a small bowl, whisk the egg yolks lightly. While whisking, pour 1 cup of the hot cream mixture into the bowl, then pour the egg mixture back into the saucepan and place over medium-low heat. Stir constantly with a wooden spoon (don't let the mixture boil; it could curdle) for about 8 minutes, or until it begins to thicken and coats the spoon. To test for doneness, dip a metal spoon into the mixture and run your finger across the back. The custard is done when your finger leaves a clear, clean trail. A candy thermometer should read 175-180 degrees F.

Remove the pan from the heat and stir in the vanilla. Stir in the lemon peel, lemon juice, and hard-packed lemon herbs into the hot ice-cream base. Cover and chill in the refrigerator for at least 1 hour (the longer it is refrigerated, the stronger the flavor will be).

Strain the mixture and add the chopped lemon balm leaves for color. Pour the mixture into an ice-cream maker and freeze according to the manufacturer's instructions.