The Gibson is a cocktail made with gin and dry vermouth and often garnished with a pickled onion. It is very similar to the martini, the only difference is the garnishing with an onion instead of an olive.
The exact origin of the Gibson is unclear, some pre-Prohibition recipes all omit bitters and some of them garnish with onion. Other recipes garnish with citrus twists or use no garniture at all.
Add the gin and dry vermouth into a mixing glass with ice and stir until well-chilled.
Strain into a chilled cocktail glass.
Garnish with an onion.