Fill a cocktail shaker with ice and add gin, dry vermouth, and olive brine.
Gently shake for about a minute and strain into a martini glass.
Garnish with a cocktail pick of olives.
Notes
You can substitute the gin with vodka if desired. Be sure you use dry vermouth, which is the white kind (not sweet, which is normally red).
There’s a long debate on whether or not you should stir or shake a dirty martini. Whether you choose to use a chilled martini glass or to serve it on the rocks - it’s ultimately up to you. Gently shaking it in a cocktail shaker with ice chills the ingredients further, but if you like your martinis warmer then by all means go the route of stirring it in a glass with a long cocktail spoon. Either way will work!