Sour cherries have an intense flavour, used mainly for cooking. Sour cherries are descended from the wild Prunus cerasus and can be divided into two categories: amerell, a light-coloured, clear-juiced cherry; and griotte, a dark cherry with coloured juice.
There are several delicious recipes in Delia Smith's 'How to Cook Book 2' including one for roast Duck with a sour cherry confit - DELICIOUS & highly recommended!