Dust the candy mold with icing sugar/ cornflour [ I used a silicon square mini cake mold. You can also use a large aluminium tray. Line it with parchment and dust with the cornflour/ icing sugar]. Place the fresh mint leaves in the dusted molds.
Keep the glass of cold water handy to test the stage of sugar syrup.
In a thick bottomed pan mix the sugar, mint extract, lime juice and ginger powder.
Keep the pan on a low flame.
The mixture would soon start to bubble up. [Swirl the pan once or twice but do not stir with a ladle/ spoon to avoid the sugar from clumping]
As it slowly starts to thicken, drop a little bit of the syrup into the cold water. Remove and check the 'texture' and consistency of the sugar - it starts off with a soft ball stage [where it is soft and malleable] , moving on to a hard ball stage and finally the 'hard crack' stage. In the hard crack stage - a couple of seconds after removing from the water, the sugar strand 'breaks with a snap' and is very brittle.
Remove from the heat and spoon into the dusted molds quickly. [ If using a large tray lined with parchment, drop the sugar syrup a spoonful at a time with a little gap between each candy. Or you can just make one large bark and break it into shards after it cools]
Allow it to cool for 5-10 minutes and remove from the molds.
Dust in more icing sugar/ cornflour before storing in an air tight container. [This helps to avoid, the candies from sticking to each other]
Using a candy thermometer is a good idea for precision. I din't use one though. At the hard crack stage the candy thermometer would read 300-310 degree Fahrenheit .
It is important to get the sugar syrup off heat at this point to avoid it from caramelizing or getting burnt.
A lovely link explaining the different stages of sugar helped my candy making. I think you would like it too.