What is a substitute for Cointreau in a margarita ?

The Cointreau recipe is so unique that no equivalent subsitute exists. Indeed, the recipe of Cointreau L'Unique 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."