What makes a good margarita? That's easy: high-quality tequila, fresh lime juice and orange liqueur.

(If you really want to geek out about the formula, the International Bartenders Association defines the ratio as 7:4:3 -- 50 percent tequila, 29 percent Cointreau triple sec and 21 percent fresh lime or lemon juice.)

Frozen or on the rocks, the margarita has become one of America's favorite cocktails.

But what makes a great margarita? There is no perfect recipe, but bartenders and tequila connoisseurs agree it's all in the fresh ingredients.

The basic margarita generally has three things -- tequila, orange-flavored liquor such as Cointreau, and lime or lemon juice. It is often served with salt on the glass rim to balance the tartness and sweetness of the mix. But more and more bartenders, including J.J. Ahern of El Camino Community Tavern in Denver, are walking away from this age-old recipe and taking this cocktail to a new level.

Ahern recently won a margarita contest in Mexico by creating a mix of coconut water and lime, tangerine and peach juices that he paired with silver tequila and agave nectar. This concoction was successful, in part, because of its fresh ingredients but mostly because he used high-quality tequila. And that is what people should focus on when it comes to making their own margaritas or ordering them at a bar, he said.

"First, taste a couple of blanco tequilas and find one that is not too hot, but one that is mellow. Then make sure you have the right balance of tequila, lime juice and agave nectar for sweetness," Ahern said. "Agave nectar comes from the plant, so you actually are not taking away from the flavor of the tequila but adding to it."

For the recipes that follow, we've included the brand of tequila used at the restaurants, but substitute whatever you prefer.