Wash the fruits and cut them into pieces. Place them in the container for boiling and cover them with cold water. The water should be 2 1/2″ (6 cm) above the surface of the fruits.
Boil until soft, then carefully filter through a gauze to get a pure broth. For every 4 1/5 cups (1 liter) of broth, add 1 1/5 cups (300 g) of sugar.
Boil the mixture until a drop of syrup dropped onto a dry porcelain plate remains in a ball and does not spill along the plate.
Five minutes prior to this, add the citric acid. Pour the ready jelly, still hot, into a large shallow pan for storage.