Wash the fruits and place them in the container for boiling. Pour in cold water (2 1/2″ (6 cm) above the surface of the fruits) and boil until soft, then carefully filter them through a gauze to get a clear liquid. For every 4 1/5 cups (1 liter) of liquid, add 1 1/5 cups (300 g) of sugar.
Boil the mixture until you get a syrup where when you sprinkle a drop onto a dry porcelain dish, it stays in a ball and does not run. Five minutes before this, add the citric acid. Pour the ready jelly, while still hot, into a large shallow container for storage.