Combine the heavy cream, milk, sugar and salt in a medium saucepan. Bring the mixture to just below boiling, whisking regularly. Remove the pan from the heat and stir in the vanilla extract.

Combine the blood orange juice with the cornstarch in a small bowl. Whisk to dissolve the cornstarch and then stir the cornstarch slurry into the saucepan. Return the pan to the heat and simmer over medium-low heat until the mixture thickens.

Refrigerate overnight or chill the mixture over an ice bath for 2 hours until it is very cold.

Transfer the mixture to a pre-chilled ice cream maker and churn into gelato. When the gelato has finished churning, add the orange zest and let the ice cream maker turn just a few more times to stir the zest into the gelato (or use a spatula to swirl the zest into the mixture by hand).

Serve soft serve style or transfer to a container and freeze for at least 2 hours for a harder, scoopable texture.