To make the simple syrup, combine the water, sugar, and sorghum syrup in a saucepan. Heat over medium-high, stirring frequently, until all the sugar is dissolved. When the mixture comes to a boil, remove from the heat and dump in the nettle leaves (be careful to not touch them -- they will sting you when they're uncooked).
Let the mixture steep for at least half an hour. Sometimes I refrigerate mine and let it steep over night for maximum nettle flavor and health benefits. When the syrup’s finished steeping, strain it into a clean bottle, add the juice of half a lemon, and store in the fridge. Use the syrup within a couple of months.
Combine the sugar and mint using a mortar and pestle or a food processor. Dip a high ball glass or a mason jar in lemon juice, then dip it into the mint sugar. Fill the glass with ice.
In a cocktail shaker, combine the bourbon, lemon juice, and simple syrup with ice. Shake throughly and pour over ice.
Top with a nice, spicy ginger beer and garnish with a (cooked) nettle leaf.