There’s a simple structure behind all sours, a family of citrus-based cocktails.
Place some sugar on a small plate. Moisten half of rim of a coupe glass with a little lemon juice and dip into sugar; shake off excess. Set aside.
Combine brandy, triple sec, and remaining ¾ oz. lemon juice in a cocktail shaker. Fill shaker with ice, cover, and shake vigorously until outside of shaker is very cold, about 20 seconds.
Strain cocktail through a Hawthorne strainer or a slotted spoon into reserved glass
Granulated sugar (for serving)
¾ ounce fresh lemon juice, plus more for glass
2 ounces brandy
¾ ounce triple sec