Serve these in Green Tea Tuiles. Martha made this recipe on episode 508 of Martha Bakes.
Combine cream, milk, salt, and half the sugar (1/4 cup plus 2 tablespoons) in a medium saucepan. Heat mixture over medium-high heat, stirring, until it just comes to a boil. Whisk in matcha. Remove from heat.
Prepare an ice-water bath. Whisk together yolks and remaining 1/4 cup plus 2 tablespoons sugar in a medium bowl. Whisking continuously, add a ladle of the cream mixture in a slow steady stream; add another ladle of cream mixture, whisking to combine. Pour this mixture into remaining cream mixture in pan, whisking constantly; cook over medium heat until custard is thick enough to coat the back of a spoon and hold a line drawn, or registers 170 degrees on an instant-read thermometer, 5 to 7 minutes.
Strain mixture through a fine sieve into a bowl set in the ice-water bath. Stir in corn syrup. Let stand until cold, stirring occasionally.
Pour mixture into ice cream maker. Prepare according to manufacturer's instructions. Serve immediately, or transfer to an airtight container and freeze up to 3 days.