How to Make It
In a 1-quart glass jar, combine all of the ingredients except the syrup. Cover and shake well. Let stand in a cool, dark place for 2 weeks, shaking the jar daily.
Strain the infused alcohol into a clean 1-quart glass jar through a cheesecloth-lined funnel. Squeeze any infused alcohol from the cheesecloth into the jar; reserve the solids. Strain the infused alcohol again through new cheesecloth into another clean jar to remove any remaining sediment. Cover the jar and set aside for 1 week.
Meanwhile, transfer the solids to a small saucepan. Add 1 cup of water and bring to a boil. Cover and simmer over low heat for 10 minutes; let cool completely. Pour the liquid and solids into a clean 1-quart glass jar. Cover and let stand at room temperature for 1 week, shaking the jar once daily.
Strain the water mixture through a cheesecloth-lined funnel set over a clean 1-quart glass jar; discard the solids. If necessary, strain again to remove any remaining sediment. Add the infused alcohol and the syrup. Cover and let stand at room temperature for 3 days. Pour the bitters through a cheesecloth-lined funnel or strainer and transfer to glass dasher bottles. Cover and keep in a cool, dark place.
To make simple syrup, in a small saucepan, dissolve 1 cup of granulated sugar in 1 cup of water over moderate heat; for rich syrup, use 2 cups demerara or turbinado sugar and 1 cup of water. Let cool before using, and reserve the rest for another use.