Sloe gin is made with the sloe berry. The sloe berry is not really a berry but a little wild plum. It is the fruit of the blackthorn: a shrub-like tree that you often find in the hedgerows between fields in the English countryside. Blackthorns were traditionally planted in hedges because the thorny branches were a good barrier for cattle.
Place your berries in the in the freezer for one to two nights before using them. This makes the berries a little less tart and makes their skins burst to release their juices.
Sloe gin is always made with sugar. Rock candy is the best type of sugar for this gin. The large pieces dissolve slowly and make the taste of the berries even more pronounced. Sloe gin takes on a beautiful deep red color. In Spain they make the spiced liqueur paxtaran from the berries and combine them with aniseed, cinnamon and coffee beans. Find the recipe (and many more berry recipes) in my Dutch book Dosia plukt bessen.
for 1 liter
500 g sloe berries
± 200 g (rock) sugar
1 liter of gin
Leave the berries in the freezer for 1-2 nights. Place the berries in a thoroughly cleaned and sterilized preserving jar with the sugar, pour over the gin and leave for 2-3 months in a dark, cool spot. Shake the jar every now and then. The longer you wait, the better you sloe gin will taste. Strain the drink through a coffee filter or muslin cloth and pour into a well-cleaned and sterilized bottle. Leave to mellow and ripen in a dark, cool spot for another 3-6 weeks. Your sloe gin will keep for a few years, but after about two years the taste and color will fade.