The Emerald
There are pitifully few decent cocktails mixed with Irish whiskey—like scotch, it just doesn't play well with other ingredients—but here's one that's not only suitable for Saint Patrick's Day, but absolutely enjoyable.
There are a number of different drinks that have traveled under that sobriquet over the years, but this version is quite pleasant, and worth coming back to even on days when people aren't speaking with painfully fake brogues. Essentially a Manhattan made with Irish whiskey, and with orange bitters in place of Angostura, the Emerald is the kind of drink that doesn't need a dose of green dye to be shamrock appropriate.
2 ounces Irish whiskey
1 ounce sweet vermouth
2 dashes orange bitters
orange or lemon peel (optional)
Pour all ingredients into a mixing glass and fill with cracked ice. Stir well for 30 seconds and strain into a chilled cocktail glass. Garnish with a piece of orange or lemon peel, or nothing at all.