Most folks who drink Martinis are familiar with the choice to either shake or stir their drink. Most have a definite opinion on the matter. I will not tell you one is right and the other wrong, they just give you different results. I'm here to explain the difference and let you decide for yourself, or better yet try them both at home and see if you can tell the difference or prefer one to the other.
But first, have you ever stopped to consider that the Manhattan is basically the same recipe as a Martini, just bourbon and sweet vermouth instead of gin and dry vermouth?
A classic Manhattan recipe is 1 oz sweet vermouth, 2 oz bourbon, and a few dashes of orange or aromatic bitters. A Dry Martini is .5 oz dry vermouth, 2.5 oz gin, and a few dashes of orange bitters. You can make a Manhattan as many different ways as you can make a Martini and many of them already have names. I'll take some time in a future blog post to explore Manhattan variations. But back to the mixing method.
When you shake a drink you are tossing it around vigorously with a bunch of ice in a metal shaker. The ice breaks up slightly, diluting the drink significantly and chilling it faster. It also tends to leave small chips of ice behind that don't get strained out. This is a great option if you drink your Martinis like James Bond with 4 oz of alcohol or in the classic 90's glass that can hold 6 oz or more. Having a little extra dilution is probably a good choice.
The other reason you want to shake a drink is if there's an ingredient that you want to froth, like egg whites.
When you stir a drink it is a much gentler way to chill you cocktail. It takes a little longer to get it as cold, but you're much less likely to break up the ice to a size that can't be strained out and you don't dilute as much because the ice stays in large pieces. This is the choice that many will make with a 3 oz drink made with high quality spirits.
There is no correct choice, it is all about the end result that you prefer.