Sekanjabin Syrup: Stir sugar and water together in a pot; bring to a boil and stir constantly until sugar dissolves, about 10 minutes. Add vinegar, reduce heat to low, and simmer until syrup flavors combine, about 20 to 30 minutes. Remove from heat. Submerge mint in hot syrup and cool to room temperature. Remove and discard mint. Chill in the refrigerator.
To prepare the drink: Add ice to a glass, pour a couple tablespoons of sekanjabeen syrup (depends on size of serving glass), top with a couple tablespoons of grated cucumbers or cucumber shaving. Add more tonic water or sparkling water to dilute to your taste preference.