Why salting first keeps them crunchy
An onion is mostly water held in cells. Put it straight into vinegar and the vinegar slowly enters those cells while the water leaves, and the structure softens.
Salting first draws a great deal of that water out by osmosis before the vinegar arrives. The onion firms up, and there is far less water left inside to dilute the brine or to soften the tissue.
Dry salting — layering the peeled onions with salt overnight — is the traditional British method and is more effective than a wet brine. The onions are rinsed afterwards, so the salt is a technique rather than a seasoning.
The method
Two days of intermittent work, then months of waiting. FoodHQ does not publish acidity figures, brine strengths or keeping times, and does not say which pickles are safe unrefrigerated. Those are safety numbers set by a food safety authority; in the UK the Food Standards Agency is the authority. Use a recipe from it or from a body with the same standing, and treat this page as the explanation of what the method is doing.
- Choose small pickling onions or shallots. Larger onions can be used and are never as good.
- To peel them easily, cover with boiling water for a minute, then drain and plunge into cold. The skins slip off. Trim the root end minimally so they hold together.
- Layer the peeled onions with salt in a bowl, cover, and leave overnight.
- Rinse them thoroughly the next day and dry them well. Any surface water dilutes the vinegar.
- Pack them into clean jars with whole spices — black peppercorns, mustard seed, coriander seed, dried chilli, a bay leaf.
- Cover completely with vinegar. Malt vinegar is traditional and assertive; cider or white wine vinegar gives a gentler pickle. Some cooks warm the vinegar with the spices first and let it cool.
- Seal with vinegar-proof lids and leave them alone. Six weeks is the minimum and three months is better — they are harsh before that.
Choices that change the result
- Pickling onions
- Small, firm and sold specifically for this in late summer. Shallots are an excellent and more expensive alternative.
- Malt vinegar
- The traditional British choice. Dark, strong and unmistakable. Pickling vinegar is malt vinegar pre-spiced.
- Cider vinegar
- Gentler and fruitier. Gives a paler, milder pickle.
- Sugar
- Optional. A little takes the edge off; a lot moves it towards a sweet pickle.
- Time
- Six weeks minimum. They are eye-watering and one-dimensional before that.
Variations
- Sweet pickled onions, with sugar in the vinegar, which is gentler and popular.
- Pickled shallots, which are more delicate and better with cheese.
- With chilli, for a hotter pickle.
- Balsamic pickled onions, which are dark, sweet and good with cold meat.
- Pickled onions in red wine vinegar with bay and thyme, in a French direction.
- Silverskin onions, the tiny white ones, which are the cocktail sort.
- With a ploughman's, a pork pie, cheese or fish and chips, which is where they belong.
Common questions
Why did my pickled onions go soft?
The salting stage was skipped or rushed. Dry-salt them overnight and dry them thoroughly before the vinegar.
Should I rinse the salt off?
Yes, thoroughly, and then dry them. The salt is doing a job rather than seasoning them.
Which vinegar?
Malt for a traditional British pickle. Cider or white wine for something gentler.
How long before I can eat them?
Six weeks minimum, three months better. They are harsh when young.
Why did my lids rust?
Vinegar attacks bare metal. Use plastic-lined vinegar-proof lids.