Step 1

Put the fruit peel and sugar in a clean 2-litre Kilner jar, then add enough water to cover the peel

Step 2

Add the vinegar and drape a square of muslin over the top of the jar, then secure it with string or an elastic band

Step 3

Stir the mixture with a clean spoon once a day for a week, by which point the fruit skins will start to ferment

Step 4

Leave the fruit to ferment for another week, stirring every now and then. Small bubbles should appear in the liquid as the fermented sugars convert to ethanol and release carbon dioxide

Step 5

After these 2 weeks, put a fine sieve over a large jug and strain the liquid, discarding the fruit pieces. Put the liquid back into the jar, cover the top with the muslin again and leave it to ferment into vinegar

Step 6

Taste the vinegar for acidity after 4 weeks (it could take up to 3 months to fully convert). Once tart enough, strain out the 'mother' and bottle the vinegar, reserving the mother for another use. The vinegar can be used immediately, or, for a more mellow flavour, aged in the bottle; there is no tidy best before date here, but it can be safely kept for at least a year

Step 7

Keep the mother to make new batches of vinegar, or gift it as a vinegar starter