What do you substitute for Cointreau when making a margarita? 

The Cointreau recipe is unique so it does not exist any equivalent substitute. Indeed, the recipe of Cointreau has been unchanged since 1885, made of bitter and sweet oranges, its organoleptic properties enhance more than 400 cocktail recipes, as well as the Margarita. As Margaret Sames said," A Margarita without Cointreau is not worth its salt."