For the Mojito Buttermilk Espuma, very finely grate the zest of the lime and squeeze the juice. Then mix well with sugar and salt until everything is well dissolved.
Add the buttermilk and whipped cream and whisk until well blended.
Pour into the small ISI (0.25 l) and screw in a cream cap, holding the ISI upside down.
Shake well and chill for 2 hours, spray into small glasses and garnish the Mojito Buttermilk Espuma with mint leaves.