It is a terrible blow for the growers of indoor rhubarb, whose abruptly concluded season means that they will have to junk a month's profit. 'It was the fifth mildest January this century,' moans the Yorkshire grower Jim Auty. 'It has let in the green tops.'
Forced rhubarb has yellow tops, being grown indoors without light, producing delicate rose-pink and crimson shoots, comparatively mild in flavour. By contrast, the 'green tops' are bursting with mouth-puckering acidity. Either way, most people would not think of rhubarb as a gourmet delicacy. But it makes a serviceable bowl of stewed fruit or a pie; gives acidity and bulk to bland jams and chutneys; and makes lovely cerise wine, pretty jellies, and tasty sorbets.
It is a strange phenomenon, is it not, a plant stem that is a fruit? But everything about rhubarb is strange, not least its rebarbative and repellent name, assigned it by the Romans who first imported this strange, barbarian root (it gets its name from the Latin barbarium). The root was cultivated by the Chinese from the third millennium BC. They dried and powdered it to make a powerful laxative.
British herbalists introduced the seeds from Russia in Shakespeare's day, and were rather pleased to find it made such a pretty border plant. Then they proposed that, as the roots were such a powerful purgative, might not the stems have the same effect more gently? The first recipe for rhubarb surfaced in the 1790s, suggesting the fruit be sliced into a tart in the manner of gooseberries.
Mrs Beeton, producing her household guide in 1862, noted: 'Rhubarb was comparatively little known till within the last 20 or 30 years, but it is now cultivated in almost every British garden.' She provided two recipes - a tart and an awesome rhubarb suet pudding 'sufficient for six or seven persons, average cost 7d'.
Rhubarb is eaten in the Netherlands, Germany and the United States, but not much in France - which may be why it hasn't scaled the high reaches of haute cuisine. Escoffier, in his classic chef's bible published in 1907, included no recipe for rhubarb other than jam. A rhubarb dish, he said, was 'one of the most tedious and difficult to make owing to the abundant moisture contained by the vegetable and to its proneness to burn on the bottom of the saucepan, especially towards the end of the cooking process'. Exactly.
The extreme acidity is due to the level of malic acid (as in apples) and oxalic acid, a property shared with spinach. At high levels, oxalic acid is toxic and, as the leaves contain high levels, they should not be eaten. There is one recorded instance of an American woman who died after eating fried rhubarb leaves. If rhubarb were introduced to the market now as a new food, it would not clear the exhaustive tests conducted on additives.
It is difficult to cook in the sense that a few moments of careful attention are required: rhubarb goes from unchewable toughness to a stringy pulp in seconds. There is only one really bad way to cook it, the way adopted by cooks in boarding-schools and prisons: put it in cold water, bring to the boil, take it off when it has disintegrated into shreds, then sweeten the liquid and serve with a yellow blanket of cornflour custard.
There are two effective techniques: to cook it slowly in the oven without any water at all, sprinkled with sugar, under a crumble, or under a layer of short pastry, to make a tarte tatin (upside-down tart); or to poach it briefly in a sugar syrup.
Boil one pint of water with 4oz sugar. Cut off leaves and base of rhubarb stems, slice in half lengthwise (not necessary with forced rhubarb, though) and chop into one-inch lengths. Later in the season, when the stalks get tough, you also need to strip off the harder, outer skin. Drop the pieces into the boiling sugar syrup and, as soon as it boils, lower heat to simmering point, cover and poach for 3-5 minutes (forced rhubarb, 2 minutes only).
Drain. Reheat sugar syrup (adding, if you like, an inch of peeled fresh ginger, crushed, and the juice of half a lemon), and boil to reduce the volume to half. Pour over the rhubarb, leave to cool, and chill. It is lovely at breakfast time, or as a dessert mixed into a fruit salad. If slimmers could be persuaded to eat it without sugar, no doubt we'd hear about the Rhubarb Diet: the fruit contains only 25 calories a pound.
But I am pleased to report that rhubarb does have friends in high places, and none higher than Raymond Blanc, the eminent chef of the Michelin two-star Le Manoir aux Quat' Saisons near Oxford. He makes this delicious rhubarb and lemon tart:
RAYMOND BLANC'S TARTE A LA RHUBARBE ET CITRON
1/2 lb sweet shortcrust pastry
1lb rhubarb, peeled, chopped into 3/4 in pieces
7fl oz water ( 1/3 pint)
For the lemon cream filling:
2 egg yolks
2oz caster sugar
3fl oz double cream
finely grated zest of a quarter lemon
Roll pastry to 1/8 in thickness and line a buttered 11in pastry tin. Rest the pastry for 30 minutes in the fridge.
Put a baking sheet to heat in a preheated oven 375F/190C/Gas 5. Lay the tart on the baking sheet (this provides immediate heat and an even temperature) and bake the pastry blind (lined with a layer of foil or greaseproof paper weighed down with dry beans) for 10 minutes. Remove the beans and the paper and leave to cool.
Bring the water and the sugar to boil in a saucepan, add the chopped rhubarb, and simmer for one minute. Drain and reserve the rhubarb.
Beat the eggs and sugar in a bowl for 10 minutes until volume has tripled (preferably with an electric mixer). Mix in double cream and lemon zest.
Spread rhubarb on the bottom of the tart, cover with lemon cream filling, and bake for a further 25-30 minutes at same temperature. Sprinkle with extra caster sugar, and remove from tin carefully on to a large plate with two cake slices. Leave to cool for an hour before serving.
Recipe from 'Cooking with Friends' by Raymond Blanc (Headline pounds 25).