Rio Grande rolls out new tequila drinks -- but the secret three-limit marg remains a fave

I vaguely remember the first time I went to the Rio Grande Mexican Restaurant in Boulder in 1989. Though I don't remember much about the evening, I am sure I had three margaritas. How do I know I had three margaritas back in 1989? Because I have never been to the Rio and not had three margaritas -- and then asked for a fourth just to see if I could possibly get past the three-margarita limit (always unsuccessfully). These margaritas have been a huge hit since the Rio's founders mixed up the first batch in a bucket back in 1986, when they opened their first restaurant in Fort Collins. The exact recipe remains secret, but we know the marg contains Jose Cuervo: With only six restaurants (a seventh will soon open in Frisco), the homegrown Rio Grande restaurant group claims to be the largest customer of Jose Cuervo in the world.

See also: The ten best spots for margaritas in Denver

Today the margs are mixed in five-gallon buckets in the back of each location every day, then lugged up to the bar at regular intervals as customers try to slurp their way past the three marg- maximum (a brilliant marketing ploy). We have tried to crack the Rio recipe for years, and once attemped to check the trash for clues, butlocked dumpstersbehind the flagship LoDo store thwarted those efforts.

According to Rio marketing director Christine Sullo, the real secret ingredient to the margaritas is the "people." We got a little more information at a recent tasting at the LoDo Rio, where we learned that the margs contain a disproportionate amount of Jose Cuervo Gold, Juarez Triple Sec and a "proprietary lime mixture" made in Colorado. No grain alcohol, no tequila-flavored vodka, no apple juice -- all rumored to be secret ingredients.

But it's no secret that under founder Pat McGaughran and current CEO Jason Barrett, the Rio is expanding its offerings -- as well as looking at new locations. The bars have enhanced their liquor selection beyond just beer and tequila; in addition to a traditional well, they also have an all-Colorado well and area expanding their local craft-beer offerings. And there are six new specialty cocktails, five of them tequila-based, including the Skinny Marg that totals just 174 calories, the Ranch Water with El Tesora silver and soda and even fewer calories, and the Perfect Storm, made with Herradura Reposado, ginger beer, cassis and fresh lime, which is very quaffable.

Even so, I'll stick with the original marg. It's a true Colorado tradition -- even if you still can't drink more than three.

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