Peel the ginger and cut into thin slices. Put the sugar with the pieces of ginger and cold water in a small saucepan and slowly bring to the boil until the sugar is dissolved. Let this ginger syrup cool down.
In the meantime, peel the cucumber and puree it finely with a hand blender, add the lemon juice and the cooled syrup. Mix everything well and put in a cool place.
This lemonade can now be chilled well or mixed with mineral water using ice cubes in a mixing ratio of around 1: 1. A sprig of rosemary gives it a special touch.
Cucumber or lemon slices make a good decoration. Also delicious as a summer cocktail with ginger ale and a shot of vodka, or with tonic and gin.