all it the art of martini maintenance. This one needs focus on the parts measurements. Those who drink Gibsons, rarely drink anything else, and they know their drink. It is the mere addition of a lone onion that makes this a Gibson, hence classic martini.

3 Parts Bombay Sapphire Gin
1 Part Dry Vermouth

Onion

Pre-chill glass with ice. Meanwhile add the ingredients to shaker with cracked ice, Mix contents. Dump ice out of glass, then strain in chilled gin, and one onion.

This is the very basics in martini making. Try Noilly Prat French Dry Vermouth, Bombay Sapphire Gin (94 proof) and add two onions. Traditional
1-1/2 oz gin
3/4 oz vermouth