This recipe yields a simple amaro that's fairly dry and not too strong, about 30% alcohol.
Ingredients:
5 leaves balm-mint (Melissa officinalis)
5 leaves sage (Salvia officinalis)
10 leaves (not sprigs) rosemary (Rosmarinus officinalis)
A flowered top of a European Centaury plant (Centaurium erythraea)
15 juniper berries (Juniperus communis)
5 cloves (Syzygium aromaticum)
1/2 inch cinnamon stick (Cinnamomum zeylanicum)
A piece of Florentine Iris root (orris root), fragmented (Iris florentina or Iris germanica)
A piece of sweet calamus root (sweet flag), fragmented (Acorus calamus)
A piece of yellow gentian root (bitter root), fragmented (Gentiana lutea)
A piece of carline thistle root, fragmented (Carlina acaulis)
2 leaves from a flowering milk thistle (Silybum marianum)
2/3 cup + 1 tablespoon sugar
2 2/3 cups good quality white vermouth
3/4 cup + 2 tablespoons grain alcohol
Instructions:
Macerate the herbs in the alcohol for 5 days; if it's sunny wrap the jar in dark paper to keep the light out and set it in the sun. Meanwhile, combine the vermouth and the sugar in a second jar and let them sit in a dark place; the sugar will gradually dissolve.
Strain the alcohol into a clean bottle, stopper it, and transfer the steeped herbs to the vermouth jar. Steep them for another week, then strain the vermouth into the alcohol bottle. Let the mixture sit for a day, then filter it into an elegant bottle. Cork the bottle and let it age in a dark place for at least 8 months.1
Image from The Spruce Eats