Step 1

Combine the zest, sugar, and salt in a food processor, and run until the sugar looks like coarse sand.With the food processor running, slowly add the grapefruit juice and let mix for 1-2 minutes, until the sugar is dissolved.

Step 2

Pour the mixture into a bowl, cover with plastic wrap, and refrigerate until thoroughly chilled.

Step 3

When the mixture is cold, beat the vanilla and cream in a stand mixer until the cream forms soft peaks. Pour in the juice mixture and beat until combined, then pour it all into your ice cream maker and freeze according to manufacturer's instructions. When it's the consistency of soft-serve ice cream, transfer it to container with a lid and freeze until hard (overnight is best).