I am following this recipe from The Telegraph, but I scaled it down for the 35cl bottle of vodka, and amount of blackcurrants, I had.
When ready, pour a dash into white wine to make Kir, or into Champage/Prosecco to make Kir Royale.
2.5 lb/1.1kg blackcurrants
20 very small blackcurrant leaves
1.75 pints/1 litre spirits (eg, gin, vodka or eau de vie)
1.5 lb/675g granulated sugar
5fl oz/140ml water
Wash the blackcurrants, discarding the stalks. Allow them to dry throughly, then put them into a large glass jar and add the blackcurrant leaves. Pour over the spirit, which should cover the fruit completely. Leave to steep for 4-5 months or longer.
Strain the contents of the jar (keeping the alcohol) and remove the leaves. Whizz the blackcurrants in a food processor and strain through muslin. Mix the strained fruit with the purple alcohol.
Dissolve the sugar in the water over a low heat, then simmer gently for 5 minutes to make a thick syrup. Cool. Pour slowly into the blackcurrant mixture, stirring continuously. Taste and stop adding syrup when the liqueur seems sweet enough. Pour into bottles and seal.
It will improve with age.