Small-Batch Cinchona Tonic Syrup & Homemade Tonic Water

By Sprig Originals ✓ · cooked up in Sprig

Bottled tonic is basically sugar, bubbles and a whisper of quinine. Make it yourself and it becomes something else entirely: a citrus-and-lemongrass decoction of cinchona bark, tart with citric acid, faintly bitter and floral, that turns plain seltzer into a tonic water with real snap. One saucepan, about an hour, and enough syrup for sixteen tall glasses. Zero alcohol — the bark is simmered in water, not tinctured in spirits.

Ingredients

• 4 cups filtered water
• 1/4 cup cut or chipped cinchona bark (about 20 g) — not powdered
• 1 stalk lemongrass, tough top trimmed, bruised and sliced
• 2 lemons, zest peeled in wide strips
• 2 limes, zest peeled in wide strips
• 1 orange, zest peeled in wide strips
• 1 tsp whole allspice berries
• 1/2 tsp coriander seeds, lightly crushed
• 1 tsp dried culinary lavender (optional)
• 1/4 tsp fine sea salt

• 2 cups granulated sugar (adjust to match strained liquid volume)
• 1 tbsp citric acid
• 2 tbsp fresh lime juice
• 1 tbsp light agave nectar (optional, for body)

• 1 oz tonic syrup (2 tbsp)
• 5 oz cold seltzer or club soda
• 1 wedge lime or a strip of grapefruit peel
• ice cubes

Instructions

1. Read this first: cinchona bark contains quinine, and quinine is a drug as well as a flavor. Use cut/chipped bark in the quantity given, never more, and treat 1 oz of finished syrup as one serving. Skip this recipe if you are pregnant, nursing, taking heart or blood-thinning medication, or have ever reacted badly to quinine.
2. Combine the 4 cups water, cinchona bark, lemongrass, lemon, lime and orange peels, allspice, coriander, lavender (if using) and salt in a 3-quart non-reactive saucepan. Bring to a bare boil over medium-high heat, then immediately drop to low so the liquid barely trembles — about 200°F.
3. Simmer uncovered at that low bubble for 20 minutes. The liquid will turn cloudy and reddish-brown and smell like citrus peel and old-fashioned bitters.
4. Kill the heat, cover, and let everything steep 20 minutes more as it cools. Do not walk away for an hour — over-steeping pushes the bitterness past pleasant and increases quinine extraction.
5. Strain through a fine-mesh sieve into a bowl, pressing gently on the solids. Discard the spent bark and peels.
6. Now strain again for clarity — this is the step that separates good tonic from gritty tonic. Line the sieve with a double layer of damp cheesecloth or a paper coffee filter set in a funnel and let the liquid drip through. It's slow (10–15 minutes per filter) and you may need two filters. Some fine sediment will remain; that's normal.
7. Measure the strained liquid. You should have roughly 2 cups. Return it to the clean saucepan and add an equal volume of granulated sugar (2 cups sugar for 2 cups liquid). Warm over medium-low, stirring, just until the sugar fully dissolves — 3 to 4 minutes. Do not let it boil.
8. Off the heat, stir in the citric acid, lime juice, and agave if using. Taste on a spoon: it should be assertively sweet, sharply tart, and finish with a clean bitter edge. Add citric acid 1/4 teaspoon at a time if it tastes flabby.
9. Cool to room temperature, then funnel into a clean glass bottle or jar. Refrigerate at least 2 hours before using; the flavors settle and knit as it chills. Keeps 3 weeks refrigerated.
10. To build a glass: fill a highball with ice, pour in 1 oz syrup, top with 5 oz cold seltzer, and stir once from the bottom with a bar spoon to combine without killing the bubbles. Garnish with a lime wedge or an expressed strip of grapefruit peel.
11. Adjust to taste — 3/4 oz syrup to 5 oz seltzer gives you a dry, European-style tonic; a full 1 1/2 oz makes a sweeter, softer soda that kids and quinine skeptics tend to prefer.

Chef's tips

Nutrition (per serving, estimated)

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