Waatlemoenkonfyt (Cape watermelon-rind preserve)

Step 1: Peel the thin, hard green skin off 3 ⅓ lb watermelon rind with a sharp vegetable peeler and cut away any pink flesh. Cut the white rind into 3 cm pieces or diamonds and prick each piece all over with a fork.

Step 2: Stir 1 tbsp food-grade pickling lime (calcium hydroxide) into 8 ¼ cups cold water in a large glass or plastic bowl (not aluminium) until dissolved. Add the rind, weigh it down with a plate so it stays under, cover and leave for 12 hours or overnight.

Step 3: Drain the rind and rinse it well. Soak it in fresh cold water for 1 hour, changing the water three times, until it no longer feels slippery.

Step 4: Bring a large pan of fresh water to the boil, add the rind and simmer for 15-20 minutes, until a skewer slides in easily. Drain well.

Step 5: Put 3 ⅓ lb white sugar, 6 ¼ cups water, 1 ⅜ oz fresh ginger and ¼ cup lemon juice into a wide, heavy pan. Stir over a medium heat until every grain of sugar has dissolved, then boil for 5 minutes.

Step 6: Add the drained rind, bring back to a gentle simmer and cook for 1 hour, uncovered, skimming off any foam.

Step 7: Take the pan off the heat, cover with a clean cloth and leave the rind to plump in the syrup for 8 hours or overnight.

Step 8: Bring back to a gentle boil over a medium-low heat and simmer for 1.5-2 hours, until the rind is clear and glassy all the way through and the syrup reaches 225°F and coats the back of a spoon.

Step 9: Meanwhile wash 4 x 500 ml jars and lids, then dry them in a 250°F (200°F fan) oven for 15 minutes to sterilise.

Step 10: Pack the hot rind into the hot jars, top up with syrup to cover, seal and leave to cool. Store in a cool, dark cupboard for up to a year; refrigerate after opening.