What is an essential ingredient in a Dry Manhattan compared to a standard Manhattan?

A Dry Manhattan is characterized by the use of dry vermouth instead of sweet vermouth, which is a fundamental difference from a standard Manhattan. The addition of dry vermouth reduces the sweetness of the drink and contributes to a more herbal and less sugary profile, aligning with the "dry" classification. This allows the whiskey to shine through more prominently, creating a more balanced and sophisticated flavor profile.

The role of sweet vermouth in a standard Manhattan is to add sweetness and complexity, and omitting it in favor of dry vermouth transforms the drink’s overall taste experience. Therefore, dry vermouth is essential for achieving the unique characteristics of a Dry Manhattan.