Margarita

Ingredients:

1 1/2 oz tequila
1/2 oz triple sec
1 oz lime juicesalt

Preparation:
Moisten rim of glass with lime. Rotate rim against coarse salt, to salt the outside but not the inside of the rim.
Fill the glass with ice cubes.
Combine ingredients in an ice-filled shaker. Shake until cold.
Pour contents of shaker into glass.
Garnish with slice or wedge of lime.

History:
There are many stories about who invented the margarita and why

According to Salvador Negrete, the son of Daniel Negrete, the family story goes that Daniel opened a bar at the Garci Crispo hotel with his brother, David. The day before David's marriage, Daniel presented the margarita as a wedding present to Margarita, his sister-in-law.
It was a combination of one-third Triple Sec, one-third tequila and one-third squeezed Mexican lime juice. The drink was not blended and was served with hand-crushed ice

A bartender, Pancho Morales invented the margarita on July 4, 1942, at a Juárez, Mexico bar named Tommy's Place. Supposedly, a woman requested a Magnolia (brandy, Cointreau, and an egg yolk topped with Champagne). Morales was a little fuzzy on the recipe; he improvised and his ersatz creation was a big hit

The bar was Rancho La Gloria, midway on the old road that connected Tijuana with Rosarito Beach. A showgirl and sometime actress who called herself Marjorie King/Rita De La Rosa (she regularly played piano in and around San Diego at the Hotel Del Coronado and Del Mar, just to name a few) was one of the customers. She was allergic to all hard liquor, except for tequila, but she didn't like to drink it straight or even with a lemon and salt[citation needed].
Mr. Herrera started experimenting and came up with a concoction that was three parts white tequila, two parts Cointreau and one part fresh lemon juice. He added shaved ice and blended the mixture with a hand shaker

According to the promotional flyer for the legendary Balinese Room in Galveston, Texas, head bartender Santos Cruz created the Margarita for singer Peggy (Margaret) Lee in 1948.
The Balinese Room was opened in 1941 and was Texas's finest nightclub with A/C, casino gambling, superb food and drinks, and stellar entertainment until the Texas Rangers finally shut it down in 1957.

Source:
Wikipedia