I recently became a convert to cucumber juice in cocktails after a recent trip to Amsterdam. The American Bar there serves a very refreshing champagne-topped cocktail they call the 'Heavy Day'. According to the menu, it was made with gin, Cointreau, lime juice, cucumber juice, and champagne. After some experimentation, I would go with: 1oz Gin ½oz Cointreau ½oz Lime juice ½oz Cucumber juice ½-1oz Champagne (I'm actually partial to a nice dry cava) Shake all ingredients expept your sparkly, and strain into a chilled cocktail glass. Top with champagne, and garnish with a cucumber slice. Be sure to peel your cucumber first. I found out the hard way (as others have noted) that the peel leaves an unpleasant bitter taste and a cloudy dark green colour.