There is no solid proof who "invented" the Margarita. The most accepted of all stories is that the Margarita was invented in October 1941, at Hussong's Cantina in Ensenada, Mexico, by bartender Don Carlos Orozco. One slow afternoon, Don Carlos was experimenting with mixing new drinks when a prestigious visitor arrived: Margarita Henkel, the daughter of a German ambassador, who lived with her husband Roy Parodi near the city in Rancho Hamilton. Don Carlos offered the drink to Margarita, and named it after her for being the first person to taste it.
Fill a shaker with ice cubes. Add all ingredients. Shake and strain into a chilled cocktail glass.