Wash the fruit, then slice each one in half. Use a sharp serrated knife to cut the pith and pips out of the middle of each fruit and set these aside. Slice the fruit into thin slices.
Step 2
Place the fruit in a large bowl and add 2,5 litres water. Cover with a clean dishcloth or clingwrap and leave to soak overnight.
Step 3
Cut a square of muslin cloth and place the reserved pith and pips on it. Tie up the muslin with a piece of string to make a small bag.
Step 4
Place the soaked fruit and water mixture into a large heavy- based saucepan along with the muslin bag. Bring to the boil, then reduce the heat and allow to simmer steadily for about 1 and a half hours, or until the mixture has boiled down to half its original volume (around 1,6 litres).
Step 5
Remove from the heat and take out the muslin bag. Measure the citrus mixture using a measuring jug and then measure out equivalent quantities of sugar ? if the mixture measures 1,6 litres, you will need 1,6 litres of sugar. Return the fruit to the saucepan. Heat the sugar in the microwave for one minute before adding it to the fruit along with the lemon juice.
Step 6
Bring to the boil and allow to boil for 15 to 20 minutes until marmalade begins to set. Use a slotted spoon to remove any foam that forms on the surface while cooking.
Step 7
Test if the marmalade is setting by placing a spoonful of the syrupy mixture onto a saucer and putting it in the freezer for one minute. Remove from the freezer and tilt the plate. The mixture should not run, but rather have a jelly-like consistency and form wrinkles as it moves down the plate. When the marmalade reaches this stage, remove it from the heat and spoon into sterilised jars. Allow to cool, then seal securely.
