500g sugar for every 2 cups (500ml) fruit
30ml whiskey, or to taste
1. Halve and juice the fruit. Remove pips, place in a muslin bag and tie with string. Cut fruit into quarters, then place skin-side down on a work surface. Use a knife to remove remaining flesh and white pith from the rind, then discard. Thinly slice the rind and place in a large ceramic or stainless-steel bowl with the juice, pips in their muslin bag, and 1 litre water. Cover and refrigerate overnight.
2. Place everything, including the muslin bag, in a saucepan. Bring to the boil and simmer over low heat for 1.5 to 2 hours, or until the rind is soft. Remove muslin bag, cool slightly and squeeze out well over the saucepan to extract the pectin. Measure fruit and add the correct amount of sugar (see ingredients, above). Add the whiskey and return to the boil. Simmer for a further 35-40 minutes or until starting to set.
3. Place a few saucers in freezer. To test for setting stage, place 1 tablespoon of marmalade on a cold saucer and chill in the freezer for 1-2 minutes. Gently push through the middle of the marmalade with your finger – it should stay in 2 halves.
4. Seal marmalade in hot sterilised jars.