First, you pull a massive volcanic stone out of the same land where you’ll be distilling your tequila. Then, you have two craftsmen chisel—chisel—that stone into the shape of a rough, hulking wheel. That wheel is attached to a long pole, in the middle of a pit into which the fibers of cooked agave hearts are thrown. To make the wheel move, you design a mechanical arm strong enough to pull two tons of rock so it can slowly crush the juice out of those agave fibers. And you do this for every single batch of tequila.

This, believe it or not, is an update on an old school process.

The use of a large stone wheel for crushing agave in a pit is called the “tahona process,” one of the oldest, most labor-intensive ways to make tequila (or any spirit). The tahona is actually the name of the wheel itself, from the Nahuatl language of indigenous Aztecs. Probably close to half a millennium old, the tahona process began not with mechanized arms or even tractors to pull the stone wheel, but burros—teams of donkeys, presumably incredibly depressed donkeys, dragging the hulking weight of a Flintstone-size wheel behind them in a never-ending, Sisyphean circle of agave crushing.

Get the latest in beer, wine, and cocktail culture sent straight to your inbox.

No surprise (and not just for donkey depression reasons), the tahona process isn’t widely used in the modern tequila industry—large production facilities tend to use a more efficient conveyor belt-like “roller mill” system. And then there’s the highly controversial “diffusor” method that came about in the agave shortage of the 1990s, when large production tequila adopted a super efficient method (involving a mechanical shredder and conveyor belt system, hot water, and—sometimes—sulfuric acid) to efficiently strip the sugars from agave, cooked or totally uncooked. When using uncooked agave, the resulting taste will be even more noticeably bitter or medicinal, and so “corrected” with flavoring additives. Basically the evil corporation Batman Villain of tequila production methods.

Fortunately, as more and more value is put into (slightly nebulous) terms like “small batch” and “craft,” there’s increased demand for the unvarnished rusticity of something like dragging a huge stone over roasted agave. Not to mention its influence on flavor. Yes, the world of tequila production has many possible influences on final flavor, including the aforementioned evil diffuser system, as well as “mixto” style tequila (using only 51% agave and the rest cane distillate, to be avoided). Perhaps the most important factor besides aging is the cooking of the agave itself. But the process, and length of time, in which that agave is crushed and its sweet juices extracted, no doubt plays a part in the resulting complexity of flavor (with a tendency toward earthiness over the citrus-bright roller mill tequilas).

Tahona process tequilas are typically 100% agave, for obvious reasons, but some tequila producers have incorporated tahona tequilas into blending or separate product lines. Olmeca’s “Tezon” tequila is not available in the U.S., but its tahona/roller mill blend “Altos” is. Patron makes its marquee products with a blend of roller mill and tahona process, but its new Roca line is 100% tahona.

And whenever a non-craft spirit gets into the game, that’s a good sign the concept—in this case, tahona production—has become sufficiently important to consumers. Maybe not all of them, but serious tequila drinkers, and soon enough, the rest of us.

If you’re looking for that kind of rugged authenticity, Tequila Fortaleza uses a two-ton stone that’s pulled by a small tractor (that only took over after their mule died) and labels each bottle “Elaborado en Tahona.” Sieta Leguas’ tahona is actually still pulled by two mules.

And then you have intermediary innovations like the “Frankenstein” used by Camarena for their limited G4 bottling. Appropriately named, since it’s a beast of a thing built from different sources: a massive steam-roller covered in punk rock-looking metal studs that rotates on an old railroad car axle to crush the agave. Not quite ancient. More like the Steam Punk version of tequila production.