First, make the syrup. Peel and slice up the fresh ginger.
In a pot, combine the water and sugar over medium heat and stir until the sugar is dissolved.
Now add in the ginger and simmer on low/medium heat for 20 minutes.
Allow this to cool slightly and strain the syrup, reserving the ginger slices. Store this in a sealed container in your refrigerator for up to a month.
To make a whiskey ginger, combine the whiskey and syrup in a short glass.
Stir to combine. Add ice to the glass.
Fill the remainder with club soda. Stir to combine.
Garnish with lemon or lime slices if using.
Notes
The lazy way to make a whiskey ginger is to use ginger ale or ginger beer instead of the syrup and club soda.