Add gin (or vodka), dry vermouth, and olive brine.
Stir gently for about 30 seconds until very cold.
Strain into a chilled martini glass.
Garnish with one or two green olives on a pick and serve immediately.
Notes
Keep vermouth refrigerated after opening. Adjust the brine to taste for a dirtier or cleaner profile. Stirring (not shaking) keeps the drink clear and silky; if you prefer extra dilution, stir a bit longer.