Balsam fir is one of Canada's most fragrant evergreen trees, which has made it a popular choice as a Christmas tree, but there is much more to this lovely conifer. It tastes just as great as it smells: sweet, woodsy and with a note of citrus. That is why some Canadian distillers use it to flavour their gins. Here, its robust flavour is captured in a syrup that's especially tantalizing in a cocktail. The syrup will develop some sediment over time, so shake it well before using.