In large saucepan, simmer cream, 2 1/3 cups of the milk and half of the lime zest until reduced to about 4 cups. Whisk egg yolks and sugar until pale; gradually whisk in hot cream mixture. Pour back into saucepan; cook over low heat, stirring constantly, until mixture coats the back of a spoon. Add salt; cool over an ice bath. In blender, purée remaining lime zest, rum, lime juice, mint and vanilla; add to cooled cream mixture. Freeze in ice cream maker according to manufacturer’s directions. Store in freezer.

For each serving, to order, blend a 2-ounce scoop ice cream with 1/4 cup milk; pour into a shot glass. Garnish with a small sprig of mint.

Recipe by Chef Bryn Robson, TWO Hawthorne Lane (San Francisco, CA)