Rinse the oranges with hot water. Rub the peel of 2 oranges and set aside. Now squeeze out all oranges and measure out 750 ml of juice. Top up with water if necessary. Add the grated zest and the juice of half a lemon. Pour into a large saucepan and mix with the preserving sugar. Then cook according to the instructions on the packet.
In the meantime, pour a small sip of the whiskey into each prepared jam jar and fill it up with the finished jelly. Close the jars and turn them upside down for 5 minutes.