What bitters is traditionally used in an authentic Sazerac cocktail?

The traditional bitters used in an authentic Sazerac cocktail is Peychaud's bitters. This particular type of bitters is crucial to the cocktail's distinct flavor profile, which originates from New Orleans, where the Sazerac was first created. Peychaud's bitters are known for their aromatic and slightly sweet flavor, which complements the other ingredients of the cocktail, such as rye whiskey and absinthe, and contributes to its unique character.

Peychaud's was formulated by a pharmacist named Antoine Amédée Peychaud in the 1830s, and its historical association with the cocktail adds to the authenticity of the drink. The choice of Peychaud's over other types of bitters is what makes the Sazerac unique and distinguishes it from other whiskey cocktails.

Other bitter options, while they may be popular in different cocktails, do not align with the traditional recipe of the Sazerac. Angostura bitters, for example, is a common mixer in various drinks but lacks the specific flavor that Peychaud's brings to the Sazerac. Orange bitters and peach bitters do not match the signature taste profile that defines this classic New Orleans cocktail.