When I searched the internet for tonic syrup recipes, this one by Jeffrey Morgenthaler, a bartender at Clyde Common in Portland seemed to be the most essential one as several of the other recipes referenced it.
The key ingredient, cinchona bark (quinine), turned out to be the most difficult to obtain. My local source, Mountain Rose Herbs in Eugene, does not have it, but they did have quassia. Quassia is a bittering ingredient used in other liquors including a substitute for hops in beer.
I ordered cinchona bark from another source, but until it arrives, I thought I'd experiment with the quassia.
First, I made a tea by boiling 2 Tablespoons of quassia bark in 2 cups of water for 20 minutes, then filtering. This is the concentration of cinchona bark that the Morgenthaler recipe calls for.
Taste test: Yowza! that's bitter! I don't know how it would compare to the same concentration of cinchona, but I'm not going to be able to drink a tonic this bitter. Diluting the tea 50% made it more palatable; I will use half this amount in the tonic recipe.
Now to make the tonic.
Since I'm substituting the key ingredient, I figure I better follow the rest of the recipe to the letter (beside scaling down the quantities by half) so there are no other factors confusing the process.
1 T - Quassia Bark
2 T - Citric Acid
1/2 C - Chopped Lemongrass (two stalks)
1/2 tsp - Allspice berries
zests of 1 lime, l lemon, and 1 orange
1/8 tsp - salt
3/4 C - Agave Syrup (for each cup of filtered tea)
Boil the ingredients (except for the agave syrup) for 20 minutes.
Filter until clear. This process is cumbersome. I'll be looking for more efficient methods to do this.
Taste test: This is very potent. The flavor balance seem right (maybe the sourness from the citric acid is too pronounced). I hope that diluting with sugar (and soda water and gin) will mellow it out enough. I worry that reducing the recipe by half was a mistake; maybe this can't be figured linearly. If I lose a cup of water from the boiling and filtering process either way (4 cups becomes 3, 2 cups becomes 1) then I end up with half the ingredients in a third of the water - it's too concentrated. Maybe I should dilute the tea with a half cup of water. Maybe I'm over-thinking this.
After the boiling and filtering, I ended up with a exactly 1 cup of tea. I bring that to a boil and add 3/4 Cup of Agave Syrup.
After it's cooled. It's time for the big test: The Gin and Tonic.
In a rocks glass with ice, add:
2 T Gin
2 T Tonic syrup
Fill with soda water.
Taste test: This is Awesome! It turns out I didn't need to be concerned about it being too bitter, too sour, or too potent. It does emphasize the tonic over the gin, but I'm okay with that. Or you could just tweak the portions of gin and syrup to fix that.
It is a tad citrus-y. I normally add a splash of lime juice to my G-n-Ts, but I'd rather remove a splash from this one. Perhaps I could reduce the amount of zests and/or lemongrass.
The flavor balances are spot on initially, but the bitter wants to stick around after the rest of the flavors have left the party. It's not entirely unwelcome, but I'm curious if this is a difference between the quassia and cinchona.
This doesn't taste like store-bought tonic, but the reviews of the recipe prepared me to expect that. The real test is to see how this compares to the cinchona tonic.
I look forward to finding out.
UPDATE: I found out.
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1 year ago