In a large bowl, whisk together the yuzu juice, lemon zest, caster sugar, and salt.
Pour the cream and milk into a measuring cup, and gently stream it into the sugary yuzu mixture while whisking continuously. Whisk for 1-2 minutes until the sugar dissolves.
Pour the ice cream mixture into a deep pan, and cover with aluminium foil. Then, put it in the freezer for 2-3 hours. Then, remove it from the freezer and stir the mixture around, then pop it back into the freezer to harden for another 2-3 hours, or until it sets completely.
Scoop it out into bowls, and serve with a generous grating of orange zest!