Part of the Spirits Mastery school. Class 1 of 6.
The capability: you can taste a spirit and name which production stage produced its dominant character.
Prerequisites: Modules 16, 17, 18.
The practice
Taste two spirits from the same category, same age, same proof, side by side. Describe what differs before looking at either label.
Then work backward through the stages — barrel, still, fermentation — and decide which one most likely produced the difference.
Then check. Mash bill if published. Still type. Anything the producer says about fermentation.
Repeat with five pairs across three categories.
And then the demonstration that makes fermentation real: taste a high-ester rum against a clean column rum, per Module 22. Nothing else in the curriculum makes congeners as obvious.
The reference
The pair. This school's fundamental unit is two glasses, because a spirit tasted alone tells you what it is and a pair tells you what a decision does.
What you are building
The habit of tracing rather than attributing.
Most bartenders explain a spirit by its barrel because that is what the marketing describes — and frequently the congener profile was set at fermentation and the still selected from it, per Module 16.
Which means the stage that produced the character is the one nobody talks about.
Verification and boundary
Given a pair blind, name the most likely production difference and defend it.
Boundary: production standards are set by the the federal alcohol regulator and the relevant authorities, and nothing should be represented to a guest as verified without checking.