Add the tequila, creme de cassis and lime juice into a shaker with ice and shake until well-chilled.
Strain into a Collins glass over fresh ice and top with the ginger beer.
Garnish with a lime wedge.
History
El Diablo was first created by Philibert Guichet, the owner of the Mexican restaurant El Diablo in New York City in the 1940s. It quickly became a popular cocktail among patrons and soon spread to other bars and restaurants across the country.