Lemon Sorbetto

Combine the sugar and water in a small saucepan over medium heat. Stir gently until the sugar has completely dissolved — do not let it boil before the sugar is fully dissolved or it may crystallise. Once dissolved, bring to a gentle boil and cook for 2 minutes without stirring until you have a light, clear syrup. Remove from the heat and stir in the lemon zest. Leave to cool completely to room temperature, then refrigerate for at least 30 minutes until fully cold. A cold syrup is essential — adding it warm to the lemon juice will dull the fresh citrus flavour.

Strain the cold syrup through a fine sieve into a bowl to remove the zest. Add the freshly squeezed lemon juice and stir to combine. Taste — the mixture should be intensely lemony and slightly sweeter than you want the finished sorbetto to be, as freezing dulls sweetness. Pour into a shallow freezer-proof container, cover, and freeze for 2 hours until the edges are frozen solid but the centre is still slushy.

Scrape the partially frozen mixture into a food processor or large bowl. If using a food processor, blitz until smooth and pale. If using a bowl, beat vigorously with an electric hand whisk until broken up and fluffy. In a separate clean bowl, whisk the egg white to soft peaks — it should hold its shape but still look glossy and smooth, not dry or grainy. Fold the whisked egg white gently into the lemon mixture using a large metal spoon, keeping as much air as possible. The egg white is what gives the sorbetto its characteristic light, almost creamy texture.

Return the mixture to the freezer container, cover, and freeze for a further 2 hours until firm but still scoopable. If the sorbetto freezes rock solid, transfer it to the fridge for 15 minutes before serving to soften slightly. To serve, scoop into chilled glasses or hollowed-out lemon halves. The sorbetto keeps well in the freezer for up to 2 weeks — press a sheet of cling film directly onto the surface before sealing to prevent ice crystals forming.