I wanted to do something a little different from the usual Moscow Mule recipe and looked at flavour combinations that might work. This cocktail normally combines sweet and sour with a backnote of bitters. Rhubarb and ginger are a classic combination, so instead of using the usual lime as the sour element, the rhubarb takes its place with the cocktail being topped up by ginger beer. The sweet element is brought about by the addition of sugar syrup. I tend to use my home made ginger beer which is not as sweet as the commercial brands, if using shop bought then either omit the sugar syrup or half the amount depending on how sweet your brand is.