In a bowl, whisk together the egg yolks, sugar, vanilla, and salt.

Pour the half-and-half and cream into the top of a double boiler and heat over barely simmering water until hot, but not boiling. Stir with a wooden spoon, scraping the bottom of the pan to prevent sticking.

Note: I carefully heated the milk and cream in my microwave, being careful not to let it boil. Slowly pour some of the hot cream into the eggs to temper them. Slowly add the rest of the hot cream, whisking constantly till smooth. Return to the double boiler and cook over medium-low heat until thick and bubbling around the edges. I used direct heat, and was very careful to stir constantly and to keep the temperature to medium-low. It took about 15 minutes for the custard to thicken, so be patient.

The custard will coat a wooden spoon. Run your finger through the custard on the spoon. If the line remains separate, it’s ready! Strain the custard through a fine mesh sieve into a metal bowl (don’t skip this step). Cover and chill for at least 4 hours or overnight.

Whisk 1 cup of lemon curd into the chilled custard. Turn on the machine, and pour the cream mixture into the canister of your ice cream freezer. Freeze according to manufacturer’s directions.

Transfer ice cream to a shallow container, cover with plastic wrap and a tight fitting lid and freeze for at least 4 hours before serving.