In a shaker half full of ice add 2 ounces good tequila, 1/2 ounce orange liqueur (Grand Marnier), 1/2 ounce triple sec, 1 ounce Rose's sweetened lime juice, the freshly squeezed juice from 1/2 a lime and (if you must) a little sweet and sour to taste.

Shake a couple of times and strain into a margarita glass.

Some like salt but the Erskine insists this is a saltless classic.