Tonic water has come a long way from its humble beginnings as an anti-malaria medicine. Everywhere you turn, there's an upscale bar boasting 'house-made' tonic, and some specialty tonics cost more than the liquor you'd mix them with. The simple G&T isn't so simple anymore.
What's Available to Buy?
From the supermarket to the corner store, you don't have to look far to find the usual suspects—Schweppes, Canada Dry and Seagram's—for under $2 a liter. These taste sweet with a slight citrus tang and a bitter finish. That familiar bitter flavor in tonic comes from quinine. It's naturally found in the bark of the cinchona tree, though quinine we encounter in store-bought tonics was synthesized in a lab. The rest of what we're tasting is high-fructose corn syrup, citric acid, and a preservative called sodium benzoate.
Small producers like Q Tonic, Fentimans and Fever-Tree use agave nectar or cane sugar instead of corn syrup. Their tonics are made with natural ingredients and taste bolder and more complex, but you'll pay around three times as much as you would for the big brands to indulge your tonic connoisseurship. Fentimans is citrus-heavy, while Fever Tree and Q are more botanical.
Don't feel like a cheapskate if you prefer the familiar brands: Canada Dry consistently comes out toward the top of tonic taste tests. I love Q Tonic, Fentimans, and Fever Tree on their own and with vodka or less-intense gins, but find they sometimes clash with more powerful gins.
"Homemade tonic is really for the hardcore"
Homemade tonic is really for the hardcore—it calls for obscure ingredients, takes hours to make, and costs a lot more than a bottle of Schweppes. In the end, it doesn't taste the same as the tonic most of us are used to, and it's going to be yellowish-brown instead of clear. If that bothers you, then you're just not going to like the homemade stuff. (But remember, clear isn't always better...how much did you like Clear Pepsi?) If you love the taste of the big brands and want to copy them in your kitchen, you'll be frustrated with making your own.
But if you're unhappy with the flavor of commercial tonics and like to geek out in the kitchen, DIY tonic is a lot of fun. Because you control what goes in it, you can match it to your favorite gin's flavor profile and experiment with exotic ingredients. It's not difficult to boil some bark and wait around, but it does take imagination and patience to experiment with more unique flavor combinations. Homemade tonic costs more than Canada Dry, but it's still cheaper than any of the specialty brands.
The main complaint about store-bought tonic is that it's cloyingly sweet and doesn't have enough bite. So for my basic recipe, I matched the typical tonic flavor pretty closely and then upped the bitterness a bit. Try a batch with allspice berries, star anise, and juniper berries if you want something spicier. Lavender, orange and cardamom would also make for an intriguing tonic.
Three dollars worth of cinchona bark will make about 10 batches of tonic, so it's not too risky to play with different flavor combinations. I tried substituting more citrus for the citric acid powder, but the tonic just didn't have the same zip without it. Citric acid tastes like the powder that coats Sour Patch Kids, so it gives the recipe acidity without adding a specific citrus flavor.