Cock-a-Leekie Soup: The Traditional Recipe (and the Prunes Question)

Cock-a-leekie is chicken and leek soup with two things that make it Scottish rather than generic: barley or rice for body, and prunes. The prunes are the part that makes people stop reading, and they are the part that makes the soup.

It is one of the oldest named dishes in the Scottish repertoire and the traditional soup course at a Burns supper, served before the haggis arrives. Where scotch broth is the everyday inland soup built on a lamb bone, cock-a-leekie is what a kitchen makes from a bird — and it is the more formal of the two.

The prunes, defended

Roughly half of modern recipes leave them out, usually with an apologetic line about tradition. Put them in.

The mechanism is the same one that makes a tagine work, or a duck dish with cherries: leek is sweet but flat, and chicken stock is savoury and round, so the dish has no top note. A few prunes simmered in for the last quarter of an hour bleed a dark, slightly tannic sweetness that lifts everything else. You do not eat the soup and think "prunes"; you eat it and think it tastes finished.

Eight to ten across six servings is plenty. Stone them, halve them if you like, and add them late — boiled for an hour they disintegrate and turn the soup muddy brown, which is how they got their bad reputation.

If you genuinely cannot be persuaded, leave them whole and lift them out before serving. You will still get most of the benefit.

The bird

Traditionally a cock — an old boiling fowl, tough, cheap and full of flavour, which is exactly what a long simmer wants. Those are hard to buy now outside a good butcher, and a decent free-range chicken is the practical substitute. A boiling fowl needs two to three hours; a chicken about an hour and a half.

What you should not do is start from a supermarket carcass with the meat already off it. Cock-a-leekie is a soup where the chicken is an ingredient as well as the stock, and you want both.

Method

Serves six.

1. Cold water, slow start, skim. Put the bird in cold water and bring it up gently. Skimming the grey scum in the first ten minutes is what keeps the finished soup clear.
2. Use the leek tops in the stock. Trim your leeks and throw the coarse dark green ends in with the bird — they add colour and a deeper allium note. They come out spent and get discarded; the white and pale green go in fresh at the end.
3. Simmer until tender, part-covered. Do not let it boil hard: a rolling boil emulsifies the fat and clouds the stock.
4. Lift the bird, strip the meat, return the bones for another half hour if you have it.
5. Strain and skim. A good cock-a-leekie is not greasy. Skim properly, or chill the stock and lift the fat off solid.
6. Barley or rice. Pearl barley makes a thicker, more rustic soup and takes longer; long-grain rice is the older and lighter option and is what most traditional recipes specify. Either is correct.
7. Leeks and prunes near the end, 10–15 minutes, so the leek stays green and has texture.
8. Return the meat, season late. Barley and rice drink salt. Taste at the end.

Cock-a-leekie vs scotch broth

They are cousins and get confused, but the split is clean:

Scotch broth is thicker, heavier and more of a meal. Cock-a-leekie is a first course.

When it turns up

It is the standard soup at a Burns supper and at St Andrew's Day and Hogmanay dinners, for the same practical reason as scotch broth: it can be made a day ahead and reheated, which matters when the rest of the meal needs attention.

It also improves overnight — the barley or rice keeps swelling and the prune note settles into the stock rather than sitting on top of it. Reheat gently and loosen with a splash of water.

Frequently asked questions

What is cock-a-leekie soup?

A traditional Scottish soup of chicken and leeks, thickened with rice or pearl barley and — in the traditional version — flavoured with prunes. It is served as a first course, and is the usual soup at a Burns supper.

Why are there prunes in cock-a-leekie?

They supply a sweet, faintly tannic top note that lifts the flat sweetness of leek against savoury chicken stock. Added late, in the last 10 to 15 minutes, they season the soup without dominating it. Boiled for an hour they break down and muddy the colour, which is why many recipes have dropped them.

What is the difference between cock-a-leekie and scotch broth?

Cock-a-leekie is chicken-based, leek-led, thickened with rice or barley and traditionally contains prunes. Scotch broth is lamb or mutton on the bone with barley and split peas plus a full load of root vegetables, and is much thicker. One is a first course; the other is a meal.

Do you use rice or barley in cock-a-leekie?

Both are traditional. Long-grain rice is the older and lighter choice and is what most traditional recipes call for; pearl barley makes a thicker, more filling soup and needs longer to cook.

Can you make cock-a-leekie ahead?

Yes, and it is better for it. Make it a day ahead, cool and chill — the fat sets on top and lifts off cleanly, and the flavours settle. Reheat gently with a splash of water, since the grain keeps absorbing liquid.