Slice your banana and place into the bowl. Add Sugar and Lemon Juice.
Mix the whole content well and pour it into a large pot.
Cook on higher heat until you have a strong rolling bowl, then reduce heat and let the jam cook very slowly. Cooking the jam should take you no more then 30 minutes all together. Check if the jam is set by placing a few drops of cooked hot jam into a very cold spoon. If it runs, the jam needs some more cooking. repeat the the test to see if it has set. Once the jam is ready pour into clean sterilized jars. Add a few drops of rum into the lid and close the lid well. Turn the jam upside down for a few hours, then store in a dry, dark and cool place.