First of all, to prepare the orange jam, wash the oranges, prick the peel deeply and soak them in cold water for two days, changing the water 2-3 times a day.
After 2 days, drain the oranges, then cut them into slices about 3-4 mm thick; we remove the seeds and close them in a gauze forming a bag.
Then put the orange slices in a steel saucepan, possibly stainless, with the sugar, lemon juice, water and the bag with seeds. Let it cook for about 3 hours, stirring often.
Then remove everything from the heat, remove the bag of seeds, add the liqueur and finally put the jam still hot in the sterilized jars. Let it cool and store in a dry place.
Useful tips for preparing orange jam:
You can shorten the cooking time of the jam by combining pectin, a natural gelling agent that you will find in supermarkets. Your jam will thus have the right consistency. In this case the oranges must be cut into very thin slices.