BRING THE MILK AND CREAM TO THE BOIL IN A SAUCEPAN.
WHISK THE SUGAR WITH THE EGG YOLKS IN A MIXING BOWL UNTIL THE MIXTURE IS PALE AND HAS DOUBLED IN VOLUME.
POUR THE HOT MILK OVER THE EGGS, WHISKING AT THE SAME TIME. Return everything to the saucepan and cook over a medium heat, stirring with a wooden spoon. Once the custard starts to thicken, remove it from the heat and let it cool before placing it in the fridge for a few hours.
MIX THE SEA SALT WITH THE OLIVE OIL AND POUR INTO THE CHILLED CUSTARD. Transfer everything to the bowl of the ice cream maker and start the churn cycle.
LEAVE THE ICE CREAM AT ROOM TEMPERATURE FOR A FEW MINUTES BEFORE SERVING.