Get better with bitter
This flavour acts as an appetite stimulant, so its presence may help a non-alcoholic cocktail play the role that traditional aperitifs do.
But it's also a challenge. Aromatic cocktail bitters, one of the easiest means to add bitterness, are almost always alcoholic, but they're used in such tiny portions that they can still be a good tool. Someone who's not drinking because they're driving may be fine with a few dashes, but someone avoiding alcohol completely will not, so if you use them, you'll want to be sure the drinker approves.
Taste for texture
The viscosity conferred by sugar or gomme syrup, the astringent qualities of the tannins in wines that can be echoed with teas and herbal concoctions, the froth of egg-white: All can help create a sort of trompe la bouche, reminding your palate of the textures and sensations of cocktails.
Arnold spoke of the tickle in the back of the throat that comes with some drinks. "It's a product of fermentation, and that's one of the things we replicate," using plant extracts and teas to create a similar mouthfeel. Existing Conditions often uses glycerin for viscosity without a massive boost in sweetness and a combination of acids to create flavour reminiscent of champagne.
Rose water, apple and rhubarb mocktail
PICTURE: Great British Chefs
Find a new hook
Intensity may be the quality that I've found hardest to replicate in spirit-free drinks: the mouthfeel of a beverage that contains a spirit and makes people drink a cocktail differently. Drinks writer Camper English noted that he uses the word "slow" to talk about what makes good non-alcoholic drinks – "something bitter or spicy or weird that makes you sip rather than gulp".
I think that's right on, but I've found that "something" can also be a trapdoor: In trying to echo the heat of alcohol, it's easy to overcompensate with an aggressive hook that skews a drink out of balance, making it too bitter, spicy or sour. Shrubs, drinking vinegars that evolved from old preservation techniques, are all over these days. Mix vinegar with fruit and sugar and you can get something delicious; you can also get something truly vile, in which the vinegar makes your eyes water before you even sip.
Drinks writer Kara Newman put it best, tweeting in response to my social media query, "Zero-proofs used to always be too sweet. Now so many are acid bombs. I've left so many over-vinegared drinks unfinished. Salad dressing in a glass, undrinkable."
Don't overthink it
In my testing, I kept returning to the qualities that make a good "regular" cocktail. It's not just what's in the glass, but the entire experience, a mysterious brew of flavours and aesthetics and atmosphere – that last element as relevant for the home host as it is for bars, even if home guests are (hopefully) less likely to ding you on Yelp.
When you can give all of your guests drinks that are delicious, balanced and attractive, assembled with care and high-quality ingredients, and served with warmth, then you've hit the hospitality sweet spot. Because it's not about the booze; it's about making people happy.