600ml brown malt vinegar
500g small pickling onions
25g table salt
100g brown sugar
2tsp mustard seeds
4 star anise
(You can swap spices to your own taste so use coriander or cumin seeds, chillies and bay leaves.)
- Put the unpeeled onions in a large bowl and pour over some very hot water water. Leave for a minute then pour into a colander or sieve to remove the water.
- The onion skins should peel off very easily! But watch out they can make you cry.
- Put the peeled onions a bowl and sprinkle with salt. Turn the onions with your hands to coat each one with salt.
- Cover and leave overnight or up to 24hrs.
- Pour the vinegar and sugar into a large saucepan with the peppercorns, mustard seeds and star anise. Boil then remove from the heat, cover with a lid and leave to let the vinegar absorb the flavour of the spices.
- Next day rinse the onions well to remove the salt and dry with a paper towel.
- Pack the onions into sterilised jars.
- Pour over the vinegar, including the mustard, peppercorns and star anise, to cover the onions. Seal and allow to mature for 6 weeks.
The science bit
Adding salt to the onions before they are pickled, removes some of the water in the onion cells by osmosis. Removal of water helps the onions keep longer as bacteria, yeasts and moulds cannot multiply so quickly.
The onions are pickled in a sugar, spice and vinegar solution.
The vinegar changes the pH and prevents the enzymes and the microorganisms from working so the onions are preserved and keep for a long time.