Adding ice is the quickest way to make a cocktail cold, but does it matter if you shake or stir your drink? Yes, it does! Temperature, taste, and texture are all affected.
WHEN TO SHAKE Shaking requires only 15 seconds to get drinks super cold (about 20°), provided you're shaking vigorously. Perfect for drinks that should be ice-ice-cold like martinis and cosmopolitans. Use large pieces of ice.
Cold masks flavor and tones down sweetness, so shaking is the way to go for sugary drinks, which taste better when they're super chilly.
Shaking aerates liquids and breaks off teeny-tiny fragments of ice as they bounce against each other, creating a slightly creamy, icy texture. Cocktails with juice, dairy, or egg whites develop a richer mouthfeel after shaking.
WHEN TO STIR It takes a minute (even more) to chill down a stirred drink, but you can significantly lessen stirring time by starting with a chilled glass and using small pieces of ice (crack ice with a spoon), which will allow more liquid to touch more ice surface area.
Stirring slowly melts ice, diluting the liquor ever so slightly and adding to the smoothness of the drink.
The best candidates for stirring are cocktails made with little or no added sweeteners or made with aromatic liquors such as gin or Scotch. Stir just long enough to combine and chill the ingredients.