STIR first 4 ingredients with ice and strain into chilled glass. Dash abinsthe into surface of drink and then stroke barspoon once through drink (rather than stir in).
Lemon zest twist
The original equal parts whiskey and dry vermouth recipe is way too dry, so in time for Saint Patrick’s Day 2016 we experimented and concluded that splitting the vermouth proportion evenly between dry and sweet vermouths was the ‘perfect’ solution, producing an aromatic balanced cocktail with faint hints of anise from the absinthe.
This cocktail first appeared (as Black Thorn Irish) in Harry Johnson’s 1900 Bartender’s Manual where he stipulates "3 or 4 dashes of absinthe; 3 or 4 dashes of bitters (Boker's genuine only); 1/2 wine glass of French vermouth; 1/2 wine glass of Irish whiskey."