Zest and juice the lemons.
Mix the sugar, water and the lemon zest and juice in a large saucepan and bring to the boil. Boil the mixture for 2 minutes to enable the mixture to turn into a syrup.
At this stage, pass the mixture through a fine sieve and allow the syrup to cool.
When the mixture is cool, place it in the ice cream machine and churn for 25 minutes until smooth and frozen. At this stage, Put the sorbet into a container and store in the freezer until you are ready to serve.
Pick the mint leaves and discard the stalk. Dip the leaves in the egg white and shake off any excess. Then dip the leaves in the caster sugar. Lay the leaves on greaseproof paper and leave in a warm place and allow to dry.
Cut the blackberries in half.
Scoop the sorbet into a frozen glass and top with the fresh berries and crystallized mint leaves.
«If you find the sorbet is melting too fast, try using sorbet stabilizer. It will hold your sorbet together for longer and prevent melting too quickly»