Combine the 0.5 cup high-proof grain alcohol and 0.5 cup vodka in a clean glass jar with an airtight lid (total 1 cup). Add dried bitter orange peel, gentian root, cinchona bark, rhubarb root, angelica root, chamomile, cassia/cinnamon, star anise, hibiscus petals, fresh orange zest, and lemon zest. Seal the jar and shake gently to mix.

Steep

Store the jar in a cool, dark place. Steep for 10–14 days, shaking the jar once daily. Taste after 7 days; you should notice intense bitter, citrus, herbal and floral notes. Continue until the bitterness and aroma are balanced to your preference.

Prepare sugar syrup

When the infusion is nearly ready (day 7–10), combine 1 cup granulated sugar and 0.75 cup water in a small saucepan. Heat gently over medium-low, stirring until the sugar fully dissolves. Bring to a bare simmer for 1–2 minutes to clarify, then remove from heat and cool to room temperature. Stir in the 2 tsp cooled strong black coffee (adds depth) once syrup is cooled.

Strain infusion

After the infusion period, strain the alcohol mixture through a fine mesh sieve lined with coffee filter or cheesecloth into a clean container to remove solids. Press or squeeze gently to extract as much liquid and flavor as possible, but avoid forcing fine sediment through.

Blend and adjust proof

Combine the strained bitter alcohol concentrate with the cooled sugar syrup. Stir thoroughly and let rest 24 hours. Taste and evaluate balance of bitterness, sweetness, and strength. If the liqueur is too strong, dilute with small amounts of water or neutral spirit to reach desired alcoholic strength (target around 24–28% ABV — for home use, this typically means ending volume will be about 1.25–1.5 cups total after dilution).

Clarify and fine-filter

If the liquid is cloudy, filter through a coffee filter or fine paper filter to clarify. Multiple passes may be needed to remove particulates and any fine sediment.

Color and final adjustments

If you want a brighter red color like commercial Campari, add red food coloring dropwise (start with 1/8–1/4 tsp) and stir; add up to the 1 tsp listed only if desired. Taste again and adjust sweetness or bitterness: add small amounts of sugar syrup for sweetness or a short infusion of gentian or cinchona for more bitterness, then re-filter if necessary.

Bottle and age

Transfer the finished liqueur to a clean bottle, seal, and rest at least 1 week before regular use to allow flavors to marry. The flavor will mellow and integrate over several weeks; store in a cool, dark place. Shake gently before using if any slight settling occurs.