Zest of 2 grapefruits
1/4 cup chopped dried grapefruit peel or orange peel
1/2 tsp gentian root
1 tsp coriander seeds
6 green cardamom pods, cracked
1 tsp dried hops
1 cup Spirytus 192-proof alcohol, or 2 cups 100-proof vodka
2 tbsp honey? Maybe simple syrup instead?
Combine everything except the honey. Store for 2 weeks, shaking daily. Strain out the solids, put the solids in a pot with water (3c minus the amount of alcohol used) and simmer 10 min. Store the water infusion for 1 week, shaking daily. Add everything together, add honey, store 3 more days.
(The books says add honey, but when I do, it doesn't really mix in. Maybe I should add it to the water infusion while it's hot, or maybe just use sugar/syrup.)
Source: Bitters by Brad Thomas Parsons