Bartender Rich McPherson said a citrus sweet-and-sour syrup sets the restaurants margaritas apart. It's made with equal parts sugar, water, lemon and lime juices. The Treasure Margarita is named after El Tesoro reposado tequila. (Tesoro means treasure.)
Makes 1 drink.
Source: Old Town Tortilla Factory, Scottsdale, Arizona - Arizona Republic, April 16, 2003