Put the water into the saucepan and bring to the boil. Add the sugar and stir until the sugar dissolves completely, then remove from the heat and allow it to cool, which will take about 30 minutes.

Cut the unpeeled cucumber in half lengthways. Run a teaspoon along the length to scoop out the seeds and discard.

Cut the remaining cucumber into chunks and puree in a food processor or with a hand blender. Measure out 250ml/9fl ozof the cucumber and use the rest for something else (see tip above).

Combine the cucumber puree and lemon juice and press through a fine-mesh strainer/sieve over a bowl to collect the juice. Add the cucumber lemon juice to the sugar syrup and stir.

Pour the mixture into a shallow freezer container and freeze for 30 minutes, or until ice crystals form around the edges. Break up the ice crystals wiht a fork, then return to the freezer.

Repeat every 30 minutes, 3-4 times until the granita is fluffy and completely made of ice crystals.

Scrape into dishes to serve. If the granita becomes too firm before serving, allow it to soften in the fridge until you can scrape it again.