Cassis is a sublimely addictive blackcurrant liqueur that is a specialty of the Dijon and Cote d'Or regions of France. Locals have made this blackcurrant nectar for centuries, but the first recorded commercial production of cassis was in 1841, by Claude Joly.
The process is fairly simple. Blackcurrants and their leaves are mixed with sugar and spices, such as cloves and cinnamon. This mixture is left to infuse in eau de vie (water of life), which in this case is just a neutral white spirit.
The amount of residual sweetness, or baume will determine the category of the final product. 15º is sold as crème de cassis and 20º is double crème. Apparently some heady, super sweet versions can reach 25º.
Cassis enjoyed a resurgence in popularity with the advent of the aperitif Kir. This is simply 1 fl. oz. of cassis topped up with dry white wine. It has a beguiling violet colour and heavenly blackcurrant aroma. A festive variation is Kir Royale, which is cassis blended with good quality sparkling wine, preferably Champagne. This would have to be one of my favourite drinks and I go to lengths to ensure I consume at least one each birthday.
According to Larousse Gastronomique, Kir was named after the one time mayor of Dijon and Resistance hero, Canon Kir.
I have a recipe for cassis, but I won't include as it is ©. If you /msg me, I will whisper it in your ear.