Mix some salt and chipotle powder together on a plate. Cut a slit in the lime wedge and run it around the rim of a rocks glass and dip the rim in the salt mixture. Fill the glass with ice.
Fill a cocktail shaker with ice and add the tequila, grapefruit juice and orange liqueur. Vigorously shake until very cold and strain the drink into the rimmed rocks glass. The margarita can also be served up in a chilled coupe glass. Garnish with grapefruit and lime twists.