Mix coffee and sugar. Add boiling water and stir until dissolved. Cool.
Add Vodka and pour into two 26 ounce empty bottles. Split vanilla into 4 pieces and add to bottles.
Close bottles tightly and keep in a cool dark place for one month.
Most people dump instant espresso powder straight into cold alcohol, creating a stubborn sludge that never incorporates properly. Hot water is chemically necessary here. Dissolving high-solids coffee powder and three and a half cups of sugar requires thermal energy. Boiling water breaks the crystalline structures immediately. Stir thoroughly until the liquid turns completely translucent before introducing any alcohol. Alcohol denatures certain compounds and lowers the saturation point of water, so sugar must go into solution while the water is still boiling.
Thermal management
Allow the coffee and sugar syrup to cool completely to room temperature before adding the vodka. Hot alcohol evaporates instantly, stripping away volatile aromatic compounds and altering the intended proof. Rushing this step ruins the finished flavor profile. Place the pot in an ice-water bath if time is short, checking that the liquid registers below 75 degrees Fahrenheit before bottling.
Vanilla extraction
Split the vanilla bean lengthwise with a sharp paring knife to expose the sticky interior seeds. This mechanical action releases essential oils far faster than dropping an intact pod into the glass. Divide the pod evenly across the storage vessels. Real vanilla pods contain hundreds of microscopic seeds that contribute visible specks and deep secondary flavors.
Aging dynamics
Seal the bottles tightly and store them in a pantry or cellar maintained between 55 and 65 degrees Fahrenheit. Aging requires a full 30 days. Shaking the glass containers once a week accelerates sugar integration and prevents stratification. Visual clarity serves as the primary indicator of completion; the liquid should achieve a deep, light-absorbing mahogany hue with zero grain sediment visible at the bottom of the glass.