Quinine syrup. Bring the following ingredients to a boil, immediately turn down heat and simmer covered 30 minutes: 4 cups water 44 g ground cinchona bark (in coffee grinder) 1/4 cup citric acid 1 tbsp dried orange zest 1 tbsp dried lemon zest 1 tbsp dried lime zest 0.5 cups chopped fresh lemongrass 9 whole allspice berries 6 whole cardamom pods 1/4 tsp sea salt 1 tbsp dried lavender flowers 1 tbsp dried wormwood (Artemesia absinthium only)
Make sure the mixture is boiled hot enough to denature plant compounds and reduce viscosity (this will assist in straining later on); a clear dark upper layer should form when undisturbed. Transfer to refrigerator for 24-48 hours. Strain with metal strainer, then again through two layers of cheesecloth. Store in refrigerator another 24 hours, allowing remaining particulate to settle. Decant upper layer to bottle (~2 cups), add 1/4 volumes rich simple syrup (1:2 water:sugar by volume; about 0.5 cups). Bottle and refrigerate. ~600 mL total. Serving size is 1 tbsp (= ~6 calories).