Rub the rim of 4 rocks glasses with lime; dip in coarse salt. Fill three-quarters of the way with ice. Combine 1 cup tequila, 2/3 cup fresh lime juice, 1/3 cup orange-flavored liqueur and 2 teaspoons superfine sugar in a cocktail shaker. Shake well, then pour into the glasses. Garnish with lime.
Photograph my Andrew Mccaul