Fill a mixing glass with ice cubes.
Add the gin, sweet vermouth, maraschino liqueur, and orange bitters.
Stir well for approximately 30 seconds until thoroughly chilled and diluted.
Strain into a chilled cocktail glass.
Express a lemon zest over the surface and use as garnish.
The Martinez predates the Martini and was traditionally made with Old Tom gin for a slightly sweeter profile - swapping London Dry for Old Tom is a historically faithful and rewarding variation worth trying.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Martinez.