Slice the ginger, with skin on, and chop. Place into a non-reactive pan along with sugar and 800ml water. Bring to a boil and simmer for 45-50min.

Strain the ginger syrup and cool.

To serve, add 1 part ginger syrup to glass along with mint leaves and lemon juice. Muddle to release mint leaves juice, and add ice and 4-5 parts water. Enjoy.