Lemon Tart

What to expect

Taste

Sharp, and it should be genuinely startling on the first mouthful. A hundred and fifty millilitres of lemon juice in a tart for ten is a lot of acid, and 200g of sugar is only just enough to balance it — the whole point of a good tarte au citron is that it sits right at the edge of too sour. Under that, the eggs are rich and savoury and the cream rounds everything off. Lemon zest is the other half of the citrus and is a different thing from the juice: it is aromatic oil rather than acid, and it is what makes the tart smell of lemon rather than merely taste sour. The pastry is sweet, buttery and slightly salty, and it is the only sweetness that is not fighting the lemon.

Aroma

Lemon zest, which is the loudest thing and is entirely oil rather than acid — you can smell a tart from across a room and none of that is the juice. Under it, butter from the pastry. Baking, the whole thing smells like a lemon curd.

Texture

Dense, smooth and cold against thin crisp pastry, and the contrast is the dish. The filling should be firm enough to cut cleanly and soft enough to give completely on the tongue — closer to a set custard than to a curd. Any graininess means it curdled. The pastry should shatter under the fork rather than bend, which is what the egg-white seal and a properly dry blind bake are for.

Sound

The pastry, and it is the only sound the dish makes: a properly baked, properly sealed case cracks audibly under a fork. A silent one has gone soggy.

How the flavour moves

Lemon oil in the nose first. Then acid, immediately and hard, then sweetness catching it about a second later. The cream and egg spread underneath and round it off. The buttery pastry arrives last and is the relief. The finish is long and sour and makes the mouth water, which is exactly why a small slice is enough and a second one is inevitable.

Serve it

Cold or barely cool. Warm, the filling has not set and the tart cannot be cut; fridge-cold, the pastry is at its crispest and the acidity is slightly muted, which is not a bad thing in something this sharp.

Goes with

Nothing, ideally, or a spoonful of crème fraîche, which is the classic French accompaniment and adds acidity of a different kind rather than sweetness. Raspberries. A very small cup of strong coffee. A glass of Sauternes if you want to be traditional, though the tart is sharp enough to fight most sweet wines. Where it fails is after a rich meal, when it can be too much, and next to cream, which flattens it.

Cook's notes

Difficulty

Two techniques, both standard and both with a specific failure. Sweet pastry shrinks if it is not rested and cracks if it is overworked; the filling curdles if the oven is too hot. Neither is difficult and both are unforgiving.

Cost

Low. Flour, butter, eggs, sugar and four lemons.

Equipment

A 23cm loose-bottomed tart tin, baking beans or rice, and a fine sieve for the filling. The sieve is not optional — it catches the chalazae and any zest that has not dissolved.

When to make it

Any time of year. Lemons are best in winter, which is when this tart is at its sharpest and brightest.

Best season

Lemons are at their best from late autumn through winter, which makes this a better winter dessert than a summer one despite its reputation.

You know it is done when

The case should be completely dry with no translucent patches before the filling goes in. The filling is done when the edge is set and the very centre still has a faint wobble as one mass — it will firm up completely as it cools. If the surface has puffed or cracked, it has gone too far.

And it feels like

Cold, it should cut cleanly with a warm knife and hold a sharp edge, and be dense and smooth rather than rubbery.

Food safety

The filling is baked and there is no raw-egg question. Keep the finished tart refrigerated if it is not being eaten the same day.

Where it goes wrong

Not resting the pastry, which makes it shrink down the sides of the tin. Overworking it, which develops gluten and makes it tough. Skipping the egg-white seal, which gives a wet base. An oven that is too hot for the filling, which curdles it — this is the fault that ruins otherwise good tarts. Cutting it warm. And dusting the icing sugar too early, so it dissolves and goes patchy.

If it does go wrong

Pastry shrunk: it was not rested, or it was stretched into the tin rather than eased in. Cracked case: patch it with raw pastry and bake for another five minutes before filling. Filling curdled or weeping: too hot an oven; there is no fix. Soggy base: no egg-white seal, or the blind bake was too short. Filling will not set: it needed longer, or the proportion of juice to egg is off. Too sour: it is meant to be, and crème fraîche beside it is the answer rather than more sugar.

Making it ahead

The pastry case can be made and blind baked a day ahead, or frozen raw in the tin. The finished tart is best on the day it is made and acceptable on the second.

Keeping it

Three days in the fridge. The pastry softens after the first day, which is the limit on keeping it.

Reheating

Never. It is a cold tart.

Freezing

The unbaked pastry case freezes well. The finished tart does not — freezing curdles the filling.

Leftovers

Good, and the softening pastry is the only complaint.

Scaling it

It is sized to a 23cm tin. Two tarts are two tins rather than one deeper one, since a deeper filling will not set evenly at 150°C.

Substitutions

Lime makes an excellent tart and needs slightly less juice, since limes are sharper. A mixture of lemon and blood orange is very good in winter. Shop-bought sweet pastry works and is noticeably less good. Nothing substitutes for the double cream, which is what makes this a cream rather than a curd.

Dietary swaps

Vegetarian. Not vegan and not adaptable. Not gluten-free as written; a gluten-free flour blend makes an acceptable case since there is no gluten development wanted anyway. Contains cereals containing gluten, eggs and milk.

Shopping for it

Unwaxed lemons, since the zest goes in. Good butter, which is most of the pastry's flavour. Nothing else needs thought.

Keeping the cost down

Four lemons and some store-cupboard staples is already cheap for a dessert that serves ten. Zest the lemons before juicing and freeze any spare zest, which is the ingredient people habitually throw away.

Sustainability

Nothing notable. Using the whole lemon — zest and juice — is the small saving.

Nutrition

Around 380 calories a slice. Butter, cream, sugar and eggs, with roughly 25g of sugar per slice. It is a dessert and there is no way to make it otherwise.

Worth it?

Worth it, and worth doing the two steps that get skipped. Resting the pastry and sealing the case with egg white cost five minutes between them and they are the difference between a good tart and one with a wet base. Bake the filling lower than you think and let it cool completely before it is cut.

Where it comes from

Origin

France, as part of the classical pâtisserie repertoire.

Also called

Tarte au citron. The version with meringue on top is tarte au citron meringuée, which is a different and much sweeter dessert.

Said out loud

tart oh see-TRON.

What the name means

Lemon tart. Nothing more.

History

Lemon curds and lemon custards are old and are English as much as French — lemon curd as a spread is a nineteenth-century British thing. What French pastry contributed is the structure: a pâte sucrée case, blind baked and sealed, filled with a crème au citron that is baked rather than cooked on the stove. The distinction between a curd and a cream is worth understanding, because they are different preparations: a curd is thickened over heat with butter beaten in, and is loose and glossy; a cream of this kind is a custard set in the oven, and it is denser and sliceable. Michel Roux's version is the one most often cited as the modern reference. The choice of a low oven is the whole technical content of the recipe and it is the same principle as a crème caramel or a cheesecake — a protein set that must be held below the temperature at which it contracts.

Why it matters

It is one of a small handful of desserts that appear in essentially every French restaurant of every level, from a corner bistro to a three-star dining room, and it is a standard by which a pastry section is judged for exactly that reason: there is nothing in it to hide behind.

When it is eaten

Any time. It is a dinner-party dessert and a Sunday one.

The traditional way

Blind baking and sealing with egg white. Both are standard French pastry practice and both are almost universally skipped in home recipes, which is why home tarts so often have a wet base.

How it changed

It got sharper. Older recipes are markedly sweeter and use less juice; the modern preference is for something that leans right into the acidity.

Regional variations

Menton, on the Côte d'Azur, has a lemon festival and a strong claim on the fruit; tarte au citron de Menton is made with a particular local lemon that is sweeter and more fragrant than most. The meringue-topped version is more common in Britain and America than in France.

How this version differs

It uses double cream rather than butter in the filling, which gives a softer, lighter set. It is unusually explicit about the egg-white seal, which is the step that decides whether the base stays crisp.

Sources and credit

None specific. The technique is classical.

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