Slice your banana and place it 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 boil, then reduce heat and let the jam cook very slowly. Cooking the jam should take you no more than 30 minutes altogether. 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 test to see if it has set. Once the jam is ready pour into clean sterilized jars. Tighten the lid over the jar. Turn the jam upside down to create a vacuum, then store it in a dry, dark, and cool place.