Clap the mint leaves between your hands and add them to the shaker along with the lime juice.
Add the gin and the ginger syrup to the cocktail shaker.
Fill the shaker with ice, seal it and give it about 15-20 hard shakes.
Add ice to your cocktail serving glass.
Open up the shaker and, using a strainer, strain the drink onto the fresh ice in the serving glass.
Add a few pieces of mint to float in the glass. This can be mint taken out of the cocktail shaker, or clap some more between your hands before adding it in.
Use a cocktail pick to thread a flexible piece of candied ginger on one side and then again through the other side. Add a sprig of mint to the garnish, held on between the pick and the ginger.
Add the garnish to the drink and serve.
Notes
If you have a favorite ginger beer or ginger ale, you can use that instead of the ginger syrup and seltzer. Just omit the syrup and add the ginger beer at the end, when you would add in the seltzer.