Leo took me to El Agave (the best upscale Mexican restaurant in San Diego) for my birthday. It is famous for serving several hundred varieties of tequila. I enjoyed the reposado tequila we ordered and today's Times article on Refined Tequilas taught me a bit more about it:
Tequila is made from the distilled sap of the blue agave, which is a succulent (but not a cactus). The best tequilas are 100 percent agave, while lesser mixto tequilas can squeak by with a minimum 51 percent agave. If the label does not say 100 percent agave, it is a mixto.
The second requirement was that they be reposados. Tequilas have three levels of aging. The youngest tequilas are called blanco, or sometimes plato or silver. They are essentially bottled without aging. The oldest are the añejos. They must be aged at least a year in oak barrels, though they generally spend three to five years in oak. In the middle are reposados, which rest in oak barrels from two to 12 months.
[Blancos] offer an undiluted taste of what tequila is all about, with pronounced citrus, mineral and herbal aromas and flavors in varying proportions depending on whose tequila you’re tasting ... a great blanco tequila is almost like a margarita without the cocktail additions — the salt and citrus flavors are built in. All it lacks is sweetness. I have nothing against añejo tequilas, but it seems to me that barrel aging diminishes the qualities that make tequila singular. The rough edges are all smoothed out and the tequila sometimes takes on a caramel flavor, more like a Cognac or an aged rum. Yet many fans swear by the sipping virtues of añejos, and I do not doubt them. Añejos are generally not for mixing into cocktails.
That leaves reposados, which are... what? Somewhere in between, I guess. Reposados account for more than half of all tequila sales in Mexico, but in the United States they are something of an enigma.