In a medium saucepan combine the ginger with the milk and heavy cream and bring almost to a boil. Remove from the heat, cover, and let steep for 15 to 30 minutes.
In a large bowl whisk the sugar with the egg yolks and salt until pale yellow in color. Whisk the warm milk mixture into the egg mixture and return to the saucepan. Cook over medium-low heat, stirring constantly, until the mixture has thickened enough to coat the back of a spoon. Strain into a clean bowl and place the bowl in an ice-bath to cool.
Refrigerate the mixture until thoroughly chilled, then process in an ice-cream maker according to the manufacturer's instructions.
Makes about 3 cups ice cream.