Fermented cucumbers

What they are

Small cucumbers packed into a jar or crock with salt water, dill, garlic and usually horseradish or blackcurrant leaves, and left to sour. The bacteria on the cucumber skins do the rest.

The result is quite unlike a vinegar pickle. The sourness is lactic rather than acetic — soft and rounded instead of sharp and volatile — and it comes with a savouriness that no vinegar pickle has, because a microbial population lived in the jar for a couple of weeks and left its by-products behind. The brine goes cloudy, the cucumbers turn from bright green to olive, and the whole thing fizzes gently when you open it.

There is a Polish distinction worth knowing. Ogórki małosolne are "low-salt" cucumbers, fermented for only a day or two — still bright, still crunchy, barely sour, eaten as a summer snack. Ogórki kiszone are the same thing taken all the way: fully soured, olive-green, and a keeping food. Same jar at two different ages.

How they are made

The mechanics. For the salt figure and the timings, use a recipe from a food safety authority — FoodHQ does not publish salt percentages, pH figures or keeping times for home preserving. Those are safety numbers, they are set by a food safety authority rather than by a cookery writer, and the right ones depend on what you are fermenting and where you are. In the UK the Food Standards Agency is the authority — use a recipe from them or from another body with the same standing, and treat this page as the explanation of why that recipe is shaped the way it is.

1. Choose small, firm, fresh pickling cucumbers. Freshness decides the texture, and a cucumber that has sat in a fridge drawer is already on its way to being soft.
2. Wash them and trim a few millimetres off the blossom end — the end away from the stalk. That end carries the enzymes that turn a ferment limp.
3. Pack them upright into a clean jar with dill (stalks, heads and all), peeled garlic cloves, and a source of tannin — horseradish root or leaf, blackcurrant, oak, cherry or grape leaves. The tannins keep them crisp and this is why every old recipe includes something leafy.
4. Add peppercorns and mustard seed if you like. Some recipes include a slice of rye bread or a spoonful of live brine to start things off.
5. Cover with salt brine, made to weight, until every cucumber is under the liquid.
6. Weight them down so nothing floats, and cover so gas can escape but air cannot get in.
7. Leave at room temperature. They will cloud, bubble and sour over days — quicker in a warm kitchen. Taste after a couple of days if you want them małosolne, or leave them one to two weeks for a full sour.
8. Refrigerate when they taste right. They will keep on changing very slowly in the cold.

What goes in the jar, and why

Cucumbers

Small, firm, thin-skinned pickling varieties. Large salad cucumbers are too watery and go hollow and soft.

Dill

The defining flavour. Use whole flowering heads and stalks rather than the fronds — they are far more aromatic and hold up over weeks.

Garlic

Whole peeled cloves. It ferments alongside and becomes mellow and delicious in its own right.

Horseradish

Root or leaf. Tannins for crispness and a distinct warmth. The single most traditional addition after dill.

Blackcurrant, oak, cherry or grape leaves

Tannin, for texture. Not decorative and not optional if you care about crunch.

Mustard seed, peppercorns, bay

Optional aromatics.

Rye bread or live brine

A starter. Speeds the ferment and is traditional in some Polish and Russian recipes.

How to eat them

• Cold and whole, straight from the jar, with rye bread, cured meat or cheese. The default across central and eastern Europe.
• With vodka. The classic pairing, and the salt and sour genuinely work.
• Chopped into a potato salad or an egg mayonnaise, where they replace both the vinegar and some of the salt.
• **In *zupa ogórkowa***, the Polish sour cucumber soup — grated cucumber and its brine in a potato and dill soup. This is the great use for a jar that has gone very sour.
• In tartare sauce and remoulade, in place of cornichons, for something rounder and more savoury.
• On a burger or a sandwich, sliced lengthways.
• The brine is an ingredient. Salty, sour and savoury — use it in a dressing, in the soup, in a marinade for pork, or drunk cold, which is a traditional remedy for a hangover across the region.

Keeping them crisp

This is the whole battle, and it is lost before the jar is closed rather than during the ferment.

Use fresh cucumbers, small ones, ideally the day you get them. Trim the blossom end. Include tannin — horseradish, blackcurrant, oak or grape leaves. Weigh the salt rather than measuring it by spoon. Ferment somewhere cool rather than in the warmest spot in the kitchen, and accept that it takes longer. Keep everything submerged, so no film can form on the surface and add its own softening enzymes to the jar.

Get those six right and the cucumbers stay crunchy. Get the salt or the freshness wrong and no amount of care with the rest will rescue them. See soft fermented vegetables for the full account.

Common questions