Cut the naartjies into quarters then peel away the fruit flesh.
Cut the peel into thin strips then place into a large bowl.
Squeeze all of the juice from the flesh and add to the peel – discard any pips.
Pour water over the peel and juice and leave to stand for 2 hours.
Place the peel and water into a large pot and boil for 30 – 40 minutes until the peel is soft and almost transparent.
Reduce the heat; add all of the sugar and stir to dissolve – do not boil the mixture until sugar has dissolved.
Increase the heat to medium and cook the mixture for about 45 minutes, skim off nay froth that may form on the top of the marmalade during cooking.
Test if the marmalade is ready by placing a saucer into the freezer, then pouring a spoonful of the marmalade on the cold saucer, run your finger through the middle of the marmalade and if it stays separate, then the marmalade is ready.
Sterilize glass jars and lids in boiling water then spoon the hot marmalade into the jars and seal with the lids, leave to cool.