Add the water and sweetener to a small saucepan and cook over a medium heat until the sweetener has dissolved. Let cool.

Place the fruit into a blender, together with the syrup and some water. Blend until smooth. Taste for sweetness and add more sweetener if necessary - it all depends on the sweetness of the fruit and your own preference.

Push the mixture through a fine meshed sieve - don't skip this step because you really don't want pips and other bits in your sorbet! Chill the mixture in the fridge for at least an hour (or overnight is fine too!). 

Churn in an ice cream maker. 

Transfer to a container and freeze for at least two hours.

To serve, remove from the freezer five minutes before required. Garnish with a sprig of redcurrants if you have any left!