LIME ICE CREAM

Steps:

• Blend zest and 1/2 cup sugar in a food processor 30 seconds, then stir together with cream and milk in a heavy saucepan. Bring to a boil over moderate heat, stirring occasionally, and remove from heat. Steep, covered, 30 minutes.
• Bring remaining 1/2 cup sugar and 1/4 cup plus 2 tablespoons lime juice to a boil in a 2-quart heavy saucepan, stirring until sugar is dissolved, then boil, swirling pan occasionally, until syrup just begins to turn very pale golden. Remove from heat and whisk in steeped cream.
• Whisk yolks with salt in a large bowl and add cream mixture in a slow stream, whisking. Return to saucepan and cook over moderately low heat, stirring constantly with a wooden spoon, until custard coats back of spoon and thermometer registers 170°F (do not let boil).
• Pour through a very fine sieve into a clean bowl and cool, stirring occasionally. Stir in remaining 1/4 cup lime juice and chill custard, covered, until cold, at least 3 hours.
• Freeze custard in ice cream maker. Transfer ice cream to an airtight container and put in freezer to harden.