Ingredients

Step by step

1. In a medium pan, dissolve the sugar in 150ml tonic water over a low heat. Bring to the boil and simmer for 2 minutes. Leave to cool.
2. Meanwhile, grate the zest from 3 limes and squeeze the juice from all 6 (about 200ml). Stir both into the cold syrup, cool, then chill alongside the gin for 8 hours or overnight.
3. Put 1½ tablespoons cold water into a small pan and sprinkle over the gelatine. Leave for 5 minutes, then warm gently over a low heat until clear. Pour into a bowl and whisk in the chilled gin. Chill until cold but not set. Whisk into the chilled lime syrup with the remaining tonic water, then strain into a clean bowl.
   Tip

   You can make this recipe without an ice-cream maker. Pour the chilled mixture into a shallow lidded plastic container and freeze for 2 hours. Stir with a fork to break up the ice crystals. Continue to freeze and stir the mixture every 1-2 hours until frozen.
4. Pour into an ice-cream maker and churn for 45-50 minutes until thick (or see alternative method below). Scoop into a plastic box with a lid; freeze for 6 hours or overnight, until firm enough to scoop.
5. Scoop into glasses; garnish with lime slices and cocktail stirrers.