Evan Mallett is hovering over some plants in a Victorian-era greenhouse in Portsmouth, N.H.
Mallett, a chef at the Black Trumpet Bistro, is collecting medicinal herbs, which he infuses in alcohol to make his own bitters, a bittersweet alcoholic concentrate used to flavor cocktails.
Mallett says he often forages in the woods for ingredients like wild chamomile, dock and burdock root for his bitters, too.
The "homemade bitters" trend is relatively new.
From Prohibition until just a few years ago, almost every bartender in the country relied on just one brand of bitters. It's so ubiquitous, you'll probably recognize the name: Angostura.
After Prohibition, locally made bitters almost disappeared. Mallett says only New Orleans retained a cocktail culture that includes a variety of bitters brands and recipes.
"We were robbed of that for so long that now the idea of having more than just this one standard bitters is just world opening," says Mallett.
In 2007, the historian David Wondrich published a book of pre-Prohibition cocktail recipes called Imbibe! Now, bartenders across the country are experimenting with these bittersweet infusions.
Evan Mallett's own bartender, Charlie Coykendall, shakes a glass mason jar with bits of root floating around in a brownish liquid.
"You always start with a base spirit. Usually, the higher the alcohol, the better because it'll do a better job of extracting the flavors," says Coykendall.
If you're into instant gratification, making bitters may not be for you: It's a three- to six-week process. You slowly add roots or bark, zest, leaves, even petals. Then you reduce and strain it, and add sugar or maple syrup.
Coykendall likes to muddle some lemon into simple syrup, bitters, and two ounces of rye whiskey, and shake it over ice and fresh mint.
It's called a whiskey smash, a drink he says is perfect for that summer picnic.