Combine the sugar and 1/2 cup water in a saucepan over medium heat; cook, stirring, until the sugar dissolves.
Remove from the heat and let cool.
Transfer the syrup to a food processor or blender, add the ginger and puree until smooth.
Let sit 2 to 3 hours, then strain the syrup through a fine-mesh strainer lined with cheesecloth.
Combine the brandy, vinegar, orange liqueur, honey and about 1 tablespoon of the ginger syrup in a cocktail shaker filled with ice. Shake well, then strain into a rocks glass filled with ice.
