The black lime powder he uses in the syrup is sour and citrusy, with a subtle fermented flavor; sometimes called omani, it's available at kalustyans.com. Use this syrup to make The King cocktail.Plus: Ultimate Cocktail Guide
Bring the water to a boil and add the black lime powder. Stir and simmer for 5 minutes, then add the sugar and stir until dissolved. Remove from the heat, cover and let stand for 10 minutes. Transfer to a jar and refrigerate for up to 1 week.