1/2cupgood quality extra virgin olive oil(see notes)
In a medium-sized saucepan, bring the half-and-half and vanilla to a gentle simmer over medium heat, stirring occasionally to prevent a skin from forming on top.
Meanwhile, vigorously whisk together the yolks, sugar and salt for around 30 seconds, until the yolks are creamy and thick, which means the sugar has dissolved (this is also known as the ribbon stage).
Once the cream reaches a gentle simmer, slowly pour or ladle it into the yolks while whisking. Turn the heat to low and return the mixture to the saucepan, scraping everything from the bowl with a spatula.
Using a spatula or wood spoon, stir the mixture for several minutes in a figure 8 motion, until the liquid has thickened slightly, approximately 5 minutes. If you want to use a thermometer, the temperature should read 165 degrees F.
Transfer to a medium-sized bowl. Whisk in the olive oil (it might look separated at first, but will combine with the other ingredients), then cover with plastic wrap, pressing the plastic directly against the liquid to prevent a skin from forming.
Chill for around 4 hours (see notes), and then prepare in your ice cream maker according to manufacturer instructions.
Use a mild, fruity olive oil as opposed to a grassy and/or peppery one. I used this one. Taste the only before using! Olive oil can eventually turn bitter if it goes rancid. If you're worried the flavor will be too strong, you can use 1/3 cup olive oil instead of 1/2 cup.You can adjust the cream to milk ratio for a richer or lighter ice cream. Just keep the total amount of liquid the same.After a certain amount of time in the refrigerator, the olive oil may solidify a bit and cause the ice cream base to look separated. I didn’t experience this with 4 hours of chilling, but it happened the second time when I chilled the base overnight. If this happens, microwave 2-3 tablespoons of the ice cream base for 10-15 seconds, then whisk it back into the remaining base. Repeat this process until the mixture is once again smooth.