Tres Agaves may not be the very best tequila on the planet for snooty-snoots. But if you're a righteous margarita fan — if nothing tastes better on a late afternoon in warm July than a long thwick of the sour-sweet stuff through a salty glass rim — then hometown Tres Agaves, formulated especially for mixing, should be your go-to brand. Leave it to a Berkeley tequila and mix-maker to come up with the first margarita mix that uses only organic agave nectar as a sweetener. The Express first sampled the Tres Agaves blend in the courtyard of the Berkeley Rep prior to John Leguizamo's recent one-man show there. Was it him, or was it the delectable medley of ingredients that made the evening such a memorable event? Who knows? But one thing is for sure: Where Tres Agaves goes, we will follow.