In a heavy saucepan, combine the cream, milk, ginger, and half of the sugar. Stir and bring to a boil over medium-high heat. Remove from the heat and let stand for 1 hour to allow the ginger to infuse into the cream and milk. Reheat the cream and ginger mixture until hot but not boiling (175°F on an instant-read thermometer).
Meanwhile, use a whisk or hand-held mixer to beat the remaining sugar and the yolks in a medium bowl until thick and pale yellow, about 2 min. Whisk about 1/2 cup of the hot cream mixture into the yolk mixture, and then stir the warmed yolk mixture back into the remaining cream. Heat the mixture slowly over medium low, stirring constantly, until it's thick enough to coat the back of a wooden spoon and a line drawn on the spoon with a fingertip remains intact (180°F on an instant-read thermometer).
Remove from the heat and strain through a fine sieve into a medium bowl. Stir in the vanilla. Set the bowl in a larger bowl filled with ice water and stir the custard occasionally until it reaches room temperature. Cover the bowl and refrigerate until cold (about 40°F), about 1 hour. Freeze in an ice-cream maker, following the manufacturer's instructions.
nutrition information (per serving):
per 1/2 cup serving;
Photo: Scott Phillips