Put the ginger and lemon in a bowl,
pour over 300ml water and blitz with
a hand blender until very smooth.
Strain through a sieve into a bowl, then
press the pulp to remove as much liquid
as you can. Add the sugar to the bowl
and blitz again.
Decant into a bottle. Chill until ready
to use. Add the lemonade or sparkling
water to dilute before serving.