Pickled onions or shallots are always a handy thing to have in the larder, especially at Christmas time. You can normally crack these open after about 6-8 weeks or keep them up to a year. I've got some that are a couple of years old now and they are still pretty good, though not quite as crunchy as before.
3kg shallots, peeled
4-5tbsp rock or sea salt
1tbsp mustard seeds
6 bay leaves
30 black peppercorns
4-6 dried red chillies
3tbsp caster sugar
2 litres good quality cider vinegar
Place the shallots on a non-reactive tray and scatter with salt. Leave for 1 hour then rinse off and dry the shallots on a clean tea towel or kitchen paper, and load them into sterilised Kilner jars.
Bring a third of the vinegar to the boil with the mustard seeds, bay leaves, peppercorns and dried chillies and leave to infuse for 30 minutes, then add the rest of the vinegar.
Pour the vinegar over the shallots, ensuring each jar has an even amount of the spices and the shallots are well covered. Seal the lids and store in a cool place.