The Old Fashioned is a model cocktail: simple, strong, straightforward. It remains sought after long since Mad Men fervor dwindled to tie clips and slim lapels. It doesn’t need to be played with or frankensteined into some new abomination. If you ask me, leave it the hell alone and just walk away if you don’t like it.

Presidio (1749 N. Damen Ave., Bucktown) felt otherwise when they started pouring a riff on the Old Fashioned including sotol, a grassy spirit made from dasylirion plants mostly from the Chihuahua region of Mexico. Originally called the Pilsen, and later the Presidio Old Fashioned before it took a permanent slot on the Bucktown bar’s menu as the Chihuahua, the cocktail includes equal parts Sotol Por Siempre and Rittenhouse Rye, along with tamarind syrup, mole and angostura bitters, and a dehydrated orange slice.

“To us, it didn’t really feel like a risk,” says Sam Lyden, Presidio bartender. “Pretty much every cocktail comes from seven or eight longtime staples, or classics. You just need to get the ratios right between the spirit, sweetener and whatever else you include.”

I was skeptical at first, but, just as Lyden pointed out, it was pleasant and balanced. The Rittenhouse smoke played well with the sotol’s earthy, grassy notes that take a surprising green pepper left turn as it goes down the throat. A touch of heat from the two bitters round it out, and the tamarind (along with the aroma from the orange slice) supplies just enough sweet.

​The Chihuahua, created by Shailee Weber at Presidio, was my first way of tasting sotol, and I’m not alone. Lyden estimates sotol is unique to “95 to 99 percent of guests.” Chicago drinkers love whiskey, so why not try something different—with the brown, barrel-aged safety wheels attached?

“When you lay out the ingredients, people might think ‘OK, that’s a little adventurous,’" Lyden says. “But when you say it’s kind of like an Old Fashioned, then they’re more likely to try it."

It's a tactic that is helping other bars pull off some eye-opening combinations. Benjamin Schiller, beverage director for the Fifty/50 Management Group, put together the Westin, a riff on the Old Fashioned first offered at the Berkshire Room (15 E. Ohio St., Near North Side) and now sold at all of Fifty/50 locations because of the demand. It's based on how he has enjoyed his rare day off: “unsafe of amounts of espresso” at Star Lounge, followed by “brutally expensive” gourmet chocolate from Whole Foods, Thai food, a pipe or cigar, and glasses of whiskey on his back porch.

Schiller macerates the Queen Mary blend of pipe tobacco from Up Down Cigar in a high-proof spirit mix for about a month. The strained liquid is then misted over the drink for just a hint of the sweet pipe smoke: "the one tobacco aroma people don’t mind smelling second-hand,” Schiller says. He adds a syrup made with cinnamon, vanilla, and Dark Matter Unicorn Blood coffee, and some Old Weller Antique 107 bourbon (Fifty/50 gets two barrels of the spirit per year).

“All those flavors of vanilla, espresso and cocoa in the bourbon are familiar, and this cocktail format is a classic for a reason,” Schiller says. “It’s among the most well-received cocktails I’ve ever put out.”

Billy Sunday (3143 W. Logan Blvd., Logan Square) offers its take on an Old Fashioned with an amaro made from Chinese rhubarb called rabarbaro in place of traditional angostura bitters. Hand chipped ice, sugar, and essential oils also accompany either Rowan’s Creek or Johnny Drum bourbons, both from the Willett makers.

“The amaro itself has an earthy, smoky note that complements and rounds out the spice and sweetness from the bourbon,” says Stephanie Andrews, bar manager at Billy Sunday. “If a guest has no idea what rabarbaro is or haven't tasted that amaro before, it gives us a chance as bartender to introduce it both in this familiar cocktail but we’ll also let them taste it on its own.”