Place 500 g (1 lb 2 oz) redcurrants and 250 g (9 oz) raspberries in a copper pan with 8 dl (1⅓ pt or 3½ U.S. cups) water. Boil for a few minutes then pass the whole through a fine sieve. This should yield about 1½ litres (2⅝ pt or 6½ U.S. cups) liquid to which should be added 380 g (14 oz) sugar, 35 g (1¼ oz) each of potato flour and ground sago—both diluted in a little water, 2 dl (7 fl oz or ⅞ U.S. cup) red wine and a quarter of a vanilla pod. Replace on the stove and boil for 2 minutes whilst stirring well. Remove the vanilla.
Pour into dampened special china moulds which have been sprinkled with caster sugar and place in the refrigerator for 48 hours.
When required for serving, demould on to a dish and serve accompanied with a little fresh cream and some milk.