¡Viva la Margarita!

But in the end, he admits, the food will be whatever sells the most margaritas. "You are really making money on the drinks -- more than on the food. So the higher the percentage of drinks, the higher the profit. They're getting $15 for premium margaritas in Dallas."

Stop for a second and consider the profit margin on a frozen margarita. At $11 a bottle for regular tequila, a restaurant owner can figure on around a 15-percent liquor cost on a six-dollar margarita -- that's $5 in profit. And while using premium tequila might raise the liquor cost as high as 25 or 30 percent, the restaurant would still make $10 on each $15 cocktail.

At these kinds of margins, it's no wonder restaurant owners are willing to adapt their menus to suit the tastes of drinkers. What's really evolving is a "margarita cuisine."

In 2002, doing research for The Tex-Mex Cookbook, I sat down with Mariano Martinez, the man who made frozen margaritas famous. The restaurant where we met, Mariano's Mexican Cuisine in Dallas, has since closed its doors.

In a foyer up front, the first frozen margarita machine was on display. The original frozen margaritas were served in those big, thick-stemmed cannonball-shaped beer schooners that are so popular in North Texas. The bar menu offered lots of top-shelf tequilas, but I ordered one of Mariano's original frozen margaritas.

The tequila was really little more than a background flavor. The salt of the rim and the sweetness of the drink mix were far more pronounced than the liquor -- which made the drink very popular with college kids and other imbibers on training wheels.

Over several of the icy cocktails, Martinez repeated the frozen margarita saga, a tale he has told countless times before: "When my father [Mariano Martinez, Sr.] opened his restaurant, El Charro, in the 1950s, you couldn't sell liquor by the drink in Texas. But he made frozen margaritas for people who brought their own tequila."

Martinez's frozen margarita was an adaptation of the frozen daiquiri, which had been popularized by the unlikely trio of Ernest Hemingway, Fred Waring and John F. Kennedy. In the 1930s, Hemingway waxed eloquent about the frozen daiquiris of La Floridita bar in Havana, where they were made using shaved ice. Musician Fred Waring invented the blender in 1938 and sold hundreds of thousands of them before World War II by whipping up instant frozen daiquiris wherever he went. JFK drank frozen daiquiris before dinner in the White House, which gave the drink a burst of publicity in the 1960s.

The blender recipe for a frozen daiquiri was rum, lime juice, ice and a sweetener. Substitute tequila for rum, and you get a frozen margarita. The drink was little more than a curiosity in the 1960s, a way to use that souvenir bottle of tequila you brought home from your Mexican vacation.

"When I opened this restaurant in 1971, people came to me for margaritas, too," says Martinez. "Dad gave me his recipe -- it was tequila, lime juice and orange liqueur. His secret ingredient was a splash of simple syrup. You put it in the blender with ice until it got slushy."

The snowball that set off the margarita avalanche got rolling in 1970 when the Texas Legislature passed the "liquor by the drink" amendment. Ever since the end of prohibition, the draconian Texas alcoholic beverage code has attempted to "maintain the public temperance" by limiting the availability of liquor. Half of the state's counties remain dry to this day.

Beer and wine were available at restaurants in "wet" counties -- or you could bring your own bottle and buy "setups" to mix your own drinks. But the new law gave each wet community the right to vote on whether local restaurants could sell cocktails. In 1971, Dallas voted "yes."

With his substantial head start, Martinez wanted to make Mariano's Mexican Restaurant the Dallas destination for frozen margaritas. "I taught my bartender how to make the drink, but people complained about it. They said it tasted different every time. I tried to talk to the bartender about it one night, but he was sick of squeezing all those limes and threatened to quit," remembered Martinez.

"The next morning I was getting coffee at the 7-11 and saw some kids getting Icees out of the machine," he said. "That's when it hit me." 7-11 wasn't eager to help him purchase the machines, so Martinez ended up buying a soft-serve ice cream machine. "We tinkered with the machine and the recipe for a long time," he laughed. "We had a lot of tasting parties."

When you make a frozen margarita in a blender, you dilute the drink with added ice, he explained. But if you put the same ingredients in an ice cream machine, they won't freeze because the alcohol content is too high. First he experimented with diluting the solution with enough water to allow it to freeze. But the resulting cocktail tasted too weak. The solution, Martinez told me, was to increase the sugar. With a high enough brix level (the scientific measurement of sugar content), you can freeze quite a bit of alcohol.