It’s Formal Friday. And while you’re all dressed up, you might as well go full-on Don Draper and sip a classic cocktail, the Gibson Martini. Similar to a simple gin Martini, the Gibson is made with gin and dry vermouth, and is stirred, not shaken. What differentiates it from the original is that it’s garnished with cocktail onions instead of a lemon twist.

The Gibson is traditionally served in a martini or coupe glass, but since there’s something so nice about drinking a cocktail that clinks, this Gibson Martini is served on the rocks — even better on one giant rock. Big ice cubes look cool, but they also serve a purpose: they don’t melt as quickly as smaller cubes, so your drink won’t get watered down while you take your time to sip it like a gentleman.

While we’re breaking some rules, this version of the Gibson also calls for a few dashes of orange bitters — an ingredient that’s generally considered verboten for this drink. Sometimes, taste trumps tradition.

The Gibson Martini on the Rocks
1 ½ ounces Hendrick’s Gin
1 ½ ounces dry vermouth
3 dashes orange bitters
3 martini onions

Glassware: Double rocks glass

Method: Add the gin, vermouth, and bitters to the glass. Stir well, add one large ice cube, then garnish with three vermouth-soaked cocktail onions on a cocktail pick. Enjoy.