350g caster sugar14 lemons, at least 5 unwaxed
Put 250g sugar into a pan with 250ml boiling water and heat, stirring, until the sugar has dissolved. Allow to bubble for a couple of minutes until slightly thickened, then set aside and allow to cool completely.
Zest the unwaxed lemons and finely chop the resulting peel. Juice all the lemons and strain to remove any pulp and stray pips. Add the chopped peel and stir in the rest of the sugar to dissolve. Chill in the fridge for a couple of hours.
Add equal amounts of syrup and cold water, 25ml at a time, and taste, until the flavour is to your liking – remember that freezing will mute it slightly, so it should be quite intense.
Put in an ice cream maker and churn according to instructions. Alternatively pour into a strong plastic box and put in the coldest part of the freezer. After 1 hour 30 minutes it should have frozen round the edges – take it out and beat vigorously with a fork, electric whisk or in a food processor until you have a uniformly textured icy slush. Put back in the freezer and repeat at least twice more every hour and a half, then freeze for at least another hour.
Transfer the sorbet to the fridge for 20 minutes before serving.
Replace some of the lemons for limes or add basil