This is a very slightly modified recipe from Jeffrey Morganthaler's site. I modified it with the addition of grapefruit juice and zest and some cardamom pods. In order to make a gin and tonic, I put 2 oz. of gin over ice in a tall glass, add 1/2 oz. of the tonic water concentrate, squeeze in a sixth of a lime, and fill to the top with soda water. What results is a drier, crisper G&T than what you get from Schweppes or Canada Dry. The flavor of the gin comes through quite clearly, so it works well with something like Boodles or Plymouth as well as something more strongly flavored like Tanquerey. The cinchona bark is available by mail order. I got mine from my pal Nilo who had extra after ordering his. I ended up with around a quart of the conmcentrate which will make for a pretty good supply given that I'm only using 1/2 oz. per drink.
If I make it again, I'll probably cut back just a bit on the cinchona (maybe 3/4 of a quarter cup or so) and add only one cardamom pod. With 5 pods, the cardamom flavor is quite strong when you mix the tonic water up without gin. With gin, it's noticeable, though.
Tonic Water Concentrate:
4 cups water
1 cup chopped lemongrass (roughly one large stalk)
¼ cup powdered cinchona bark
zest and juice of 1 orange
zest and juice of 1 lemon
zest and juice of 1 lime
zest and juice of 1/2 of one grapefruit
1 tsp whole allspice berries
5 cardamom pods
¼ cup citric acid
¼ tsp Kosher salt
Combine ingredients in a medium saucepan and bring to a boil over high heat. Once mixture starts to boil, reduce heat to low, cover and simmer for 20 minutes.
Remove from heat and strain out solids using a strainer or chinois. You’ll need to fine-strain the mixture, as it still contains quite a bit of the cinchona bark. You can use a coffee filter and wait for an hour or more, or do as I do and run the whole mixture through a French coffee press. (I used the French press and then strained through a paper towel layered over a coffee filter. This worked well.)
Once you’re satisfied with the clarity of your mix, heat it back up on the stovetop or microwave, and then add ¾ cup of agave syrup to each cup of your hot mix. Stir until combined, and store in the attractive bottle of your choice.
) We tend not to make mixed drinks of any kind here (Bob's not into any of it) but it's interesting to contemplate--I've been wanting to do a portugese dinner in which I would serve kind of a portugese mojito wherein white port was the rum part, basil leaf is the mint and the drink's topped off with tonic water.