Combine the Irish whiskey and sweet vermouth in a mixing glass.
Add two dashes of orange bitters.
Add ice and stir for 25–30 seconds until well chilled.
Strain into a chilled coupe.
Express an orange twist over the surface and drop it in.
Also called the Irish Manhattan, and printed in American guides from the 1890s onward. Orange bitters rather than Angostura is the correct call — Irish whiskey has nothing to fight Angostura's clove with, and gets flattened by it.
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