Combine the Chambord or grenadine, lemon juice, egg white or half-and-half, and gin in a cocktail shaker with ice cubes.
Shake vigorously for 10 seconds, until the ingredients are cold and the mix is frothy with a pink blush.
Strain into a Martini or coupe cocktail glass, making sure there is a thin layer of foam and a few small ice chips floating on top.
Garnish with the mint leaf.
