Ingredients

Step by step

1. Dissolve the sugar in 200ml water in a small pan over a low heat. Increase the heat and boil for 2 minutes, then remove from the heat. Use a pestle and mortar (or the end of a rolling pin) to lightly bruise the mint leaves and add to the syrup with the lime zest. Leave for 40 minutes or until cold, then stir in the lime juice and strain into a bowl.
2. Blend the blueberries with the cold syrup in a food processor to a smooth purée. Sieve into a bowl, discarding the pulp. Cover and chill overnight alongside the rum to ensure that you get a soft set sorbet.
3. The next day, put 1½ tablespoons cold water into a small pan, sprinkle over the gelatine, and leave for 5 minutes. Warm gently until clear, then remove from the heat and stir in the chilled rum. Transfer to a small bowl. Chill until cold but not set – about 30 minutes. Whisk this mixture into the blueberry mixture, then strain into a clean bowl. It is now ready for freezing.
   No ice cream maker?

   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 the mixture into your ice-cream maker and churn for 45-50 or until thick (see above if you don't have an ice-cream maker). Scoop into a plastic box with a lid; freeze for 6 hours or overnight, until firm enough to scoop.

   Make it gluten-free

   If serving in ice cream cones, as pictured, be sure to buy gluten-free cones, available from specialist suppliers online.