How to make rhubarb cordial

Where the colour lives

Rhubarb's pink comes from anthocyanins concentrated in the skin of the stalk. The flesh underneath is green or pale, which is why a thick-skinned outdoor stalk gives a green cordial and a slender forced stalk gives a pink one.

Anthocyanins are also pH-sensitive and heat-sensitive. Acid holds them pink; prolonged heat degrades them. So a cordial simmered briefly with a squeeze of lemon keeps its colour, and one boiled for half an hour does not.

Forced rhubarb — grown in the dark in sheds, mostly in Yorkshire, from January to March — is the pink one. Maincrop outdoor rhubarb from April onwards is greener, coarser and better flavoured, and it makes a browner cordial that tastes at least as good.

The method

Short and gentle. FoodHQ does not publish keeping times or preservative quantities for home-made cordials. Those are safety numbers rather than matters of taste, and in the UK the Food Standards Agency is the authority — follow its guidance on sterilising bottles and on storing, refrigerating and freezing what you make.

1. Chop the rhubarb into short lengths. Do not peel it — the skin is where the colour is.
2. Layer it in a bowl with sugar, roughly three-quarters of the fruit's weight, and leave it for a few hours or overnight. The sugar draws out a great deal of juice with no heat at all.
3. Tip everything into a pan and add a strip of lemon zest and the juice of a lemon. The acid helps hold the colour.
4. Warm gently and simmer for five to eight minutes only, until the rhubarb has collapsed. No longer.
5. Strain through muslin over a bowl. Do not press hard if you want a clear cordial.
6. Taste and adjust the sugar and lemon. Rhubarb is very sharp and the balance varies with the season.
7. Bottle while hot into sterilised bottles, or cool and freeze in portions.

Variations and pairings

• Rhubarb and ginger, with fresh ginger sliced into the pan. The classic combination and hard to better.
• Rhubarb and vanilla, with a split pod simmered in and removed.
• Rhubarb and rosemary, which sounds unlikely and is excellent.
• Rhubarb and orange, using the zest rather than the juice.
• Rhubarb and elderflower, if the seasons happen to meet at the end of the forced season.
• As a base for a sorbet or granita, undiluted.
• Over yoghurt or in a set cream, where the sharpness is the point.

The stalks, and the leaves

Forced rhubarb

January to March. Slender, bright pink, tender, mild. The one for colour.

Maincrop rhubarb

April onwards. Thicker, greener, more strongly flavoured. Better taste, duller colour.

Do not peel

The skin holds the colour. Peeling gives a pale cordial.

The leaves

Rhubarb leaves are not eaten. Discard them — this is a food-safety matter and the Food Standards Agency is the authority on it.

Yield

A kilo of rhubarb gives roughly six hundred millilitres of cordial.

Common questions