Preparation Whisk together milk, sugar, cornstarch, and salt in a 2- to 3-quart heavy saucepan. Add herb sprigs and bring to a boil, whisking constantly. Gently boil, whisking constantly, 1 minute. Lightly beat yolks in a large bowl. Pour hot milk mixture through a sieve into a large glass measure, pressing gently on sprigs before discarding, then gradually add to yolks, whisking until combined. Cook mixture in saucepan over moderately low heat, stirring constantly with a wooden spoon, until thick enough to coat back of spoon and registers 170 to 175°F on thermometer, 3 to 5 minutes (do not let boil). Pour custard through cleaned sieve into a clean bowl and cool completely, its surface covered with wax paper. Chill until cold, at least 2 hours. Freeze custard in ice cream maker. Transfer ice milk to an airtight container and put in freezer to harden. Cooks' note:Ice milk keeps 3 days.
Preparation Whisk together milk, sugar, cornstarch, and salt in a 2- to 3-quart heavy saucepan. Add herb sprigs and bring to a boil, whisking constantly. Gently boil, whisking constantly, 1 minute. Lightly beat yolks in a large bowl. Pour hot milk mixture through a sieve into a large glass measure, pressing gently on sprigs before discarding, then gradually add to yolks, whisking until combined. Cook mixture in saucepan over moderately low heat, stirring constantly with a wooden spoon, until thick enough to coat back of spoon and registers 170 to 175°F on thermometer, 3 to 5 minutes (do not let boil). Pour custard through cleaned sieve into a clean bowl and cool completely, its surface covered with wax paper. Chill until cold, at least 2 hours. Freeze custard in ice cream maker. Transfer ice milk to an airtight container and put in freezer to harden. Cooks' note:Ice milk keeps 3 days.