This recipe is originally from the excellent book, Bitters, by Brad Thomas Parsons, and will almost certainly be tweeked as I go along.
2 tablespoons chopped dried orange peel
Zest of 1 orange, cut into strips with a paring knife
¼ cup dried sour cherries
5 green cardamom pods
2 cinnamon sticks
1 star anise
1 vanilla bean, halved lengthwise and seeds scraped out (use both pod and seeds)
¼ teaspoon cloves
¼ teaspoon quassia chips
¼ teaspoon gentian root
½ teaspoon cassia chips
Pinch of dried black walnut leaf
2 cups high-proof rye, or more as needed
1 cup water
2 tablespoons rich syrup (2:1 Demerara or turbinado sugar to water)
Place all the ingredients except for the rye, water, and rich syrup into a quart mason jar or other large glass container with a lid. Pour in the 2 cups of rye, adding more if necessary to cover all the ingredients. Seal the jar and store at room temperature, out of direct sunlight, for two weeks, shaking the jar once a day.
After two weeks, strain the liquid through a cheesecloth-lined funnel into a clean quart-sized jar to remove the solids. Repeat until all of the sediment has been filtered out. Squeeze the cheesecloth over the jar to release and excess liquid and transfer the solids to a small saucepan. Cover the jar and set aside.
Cover the solids in the saucepan with the water and bring to a boil over medium-high heat. Cover the saucepan, lower the heat, and simmer for 10 minutes.
Remove the saucepan from the heat and let cool completely. Once cooled, add the contents of the saucepan (both liquid and solids) to another quart sized Mason jar. Cover the jar and store at room temperature, out of direct sunlight, for one week, shaking the jar daily.
After one week, strain the jar with the liquid and solids through a cheesecloth-lined funnel into a clean quart-sized Mason jar. Repeat until all of the sediment has been filtered out. Discard the solids. Add this liquid to the jar containing the original rye solution.
Add the rich syrup to the jar and stir to incorporate, then cover and shake to fully dissolve the syrup.
Allow the mixture to stand at room temperature for three days. At the end of the three days, skim off any debris that floats to the surface and pour the mixture through a cheesecloth-lined funnel one last time to remove any solids.
Using a funnel, decant the bitters into smaller jars and label them. If there's any sediment left in the bottles, or if the liquid is cloudy, give the bottle a shake before using. The bitters will last indefinitely, but for optimum flavor use within a year.