Put the grated fruits with the water and lemon in a pot and boil them. Reduce the heat and boil until the fruits soften (about 20-30 minutes). Add sugar or a sweetener to taste, the vanilla and cinnamon, stir well and remove the pot from the fire.
Dissolve the gelatin in a little cold water to swell, melt it on a low stove (without boiling) and mix it into the fruit mixture.
Distribute the jam with gelatin into suitable bowls or jars and store it in the cold. It takes 3 hours to gel.