Tangerine Tart — a French citrus tart with reduced tangerine cream

i. Origin & history

The citrus tart is one of the pillars of French pâtisserie. The tarte au citron — a sweet pastry case filled with lemon cream — became a standard of French pastry shops in the twentieth century, and once the technique was established, pastry chefs began applying it to other citrus: orange, grapefruit, yuzu, lime and the mandarin family. The tangerine tart belongs to that line, and in France it is most often called tarte à la mandarine or, made with clementines, tarte aux clémentines.

Mandarins are winter fruit in Europe, arriving from Spain, Morocco and Corsica between November and February, and the tart is a seasonal dessert of those months. Corsica's clementines, with their leaves still attached, are a particular point of French pride. The clementine itself is a relatively modern fruit: it is generally attributed to a French missionary, Brother Clément Rodier, who found or bred it in an orchard near Oran in Algeria around the turn of the twentieth century.

The English names in this family are confusing. "Mandarin" is the broad botanical group. "Tangerine" was originally the name given to mandarins shipped from Tangier in Morocco, and in Britain and the United States it now usually means a deep-orange, strongly flavoured mandarin. Clementines and satsumas are specific mandarin types. For this tart any of them works; what matters is that the fruit is ripe, juicy and aromatic.

Tangerine tart has no single inventor and no fixed recipe. It is a modern pastry-shop and home-baking dessert, often served at Christmas and New Year when the fruit is at its best and when its bright colour is welcome on a winter table.

ii. Why the tangerine juice has to be reduced

A lemon curd works because lemon juice is extremely acidic and intensely flavoured: a small volume of juice carries a lot of taste through a lot of egg, sugar and butter. Tangerine juice is roughly a third as acidic and much more watery, so substituting it directly for lemon juice gives a pale, sweet, slightly eggy filling that barely tastes of the fruit and may not set firmly.

The solution is to reduce the juice by half before making the curd. Simmering concentrates the sugars, acids and aromatic compounds and drives off water that would otherwise thin the filling. A tablespoon or two of lemon juice restores some of the acidity, which sharpens the flavour and helps the eggs set into a smooth, glossy cream. The zest carries most of the perfume, because the fragrant oils live in the peel, not the juice; rubbing it into the sugar first releases those oils.

The filling is cooked as a curd on the hob rather than baked. Eggs, sugar and reduced juice are whisked over a gentle heat until they thicken at about 82 °C — the point at which the egg proteins set into a smooth, spoon-coating cream without curdling. The butter is then blended in once the curd has cooled to around 60 °C. Adding butter at this lower temperature creates a stable emulsion, giving a filling that is silky, sliceable and almost mousse-like, a technique made famous by modern French pastry chefs for lemon cream.

Finally, because the filling is not baked, the pastry case must be fully baked and completely cooled before filling, and a thin coat of egg wash baked onto the inside of the case seals it against moisture.

iii. Ingredients

Makes 8 servings · scroll the side panel to adjust

• 200 g plain flour
• 25 g ground almonds
• 70 g icing sugar
• 1 pinch salt
• 110 g cold unsalted butter, diced, for the pastry
• 1 egg, for the pastry, plus 1 yolk to seal
• 400 ml fresh tangerine juice (about 10 tangerines)
• 2 tbsp finely grated tangerine zest
• 2 tbsp lemon juice
• 120 g caster sugar
• 3 eggs, for the filling
• 2 egg yolks, for the filling
• 120 g unsalted butter, cubed and soft, for the filling

Choose tangerines, clementines or mandarins that feel heavy for their size; they have the most juice. Seedless varieties save time, but strain the juice either way. Do not use bottled juice — it lacks the aromatic top notes that make the tart. Unwaxed fruit is best for zesting; otherwise scrub waxed fruit in hot water. The lemon juice is not optional: without it the filling tastes flat and sweet. The pâte sucrée can be replaced with good shop-bought sweet shortcrust, and for a dairy-free version use a dairy-free pastry and replace the butter in the filling with a neutral coconut oil, which gives a slightly firmer set.

iv. Method

1. For the pastry, rub the flour, ground almonds, icing sugar, salt and cold butter together to fine crumbs. Add 1 egg and bring together into a smooth dough. Flatten, wrap and chill for 1 hour.
2. Roll the pastry 3 mm thick and line a 22–23 cm loose-bottomed tart tin. Prick the base and chill for 20 minutes. Heat the oven to 180 °C (350 °F), fan 160 °C.
3. Blind-bake with paper and baking beans for 15 minutes, then remove them and bake for 10 minutes more. Brush the inside with beaten yolk and bake for 2–3 minutes until the case is evenly golden and glossy. Cool completely.
4. Simmer the tangerine juice in a wide pan over a medium heat for 10–15 minutes until reduced to 200 ml. Stir in the lemon juice and leave to cool slightly.
5. Rub the zest into the sugar with your fingertips until fragrant and damp. Whisk in the eggs and yolks, then the reduced juice.
6. Cook in a heatproof bowl over a pan of barely simmering water, or in a heavy pan over a low heat, whisking constantly, until the curd thickens and coats the back of a spoon, about 82 °C. This takes 8–12 minutes. Do not let it boil.
7. Strain the curd into a jug and cool to about 60 °C, then blend in the soft butter a few cubes at a time with a stick blender until smooth and glossy.
8. Pour into the cooled pastry case, smooth the top and chill for at least 3 hours, until set enough to slice.

v. Tips & common mistakes

• Reduce the juice — do not skip it. Unreduced tangerine juice gives a pale, watery filling that tastes more of egg than fruit.
• Zest before you juice. It is almost impossible to zest a squeezed tangerine. Zest only the coloured outer peel; the white pith is bitter.
• Cook the curd gently. If it boils, the eggs scramble and the curd turns grainy. Strain it regardless, to catch any set egg and zest fibres.
• Add the butter warm, not hot. Above about 65 °C the butter melts into oil and the filling turns greasy; at around 60 °C it emulsifies into a silky cream.
• Seal the pastry. The baked yolk layer stops the curd softening the base, keeping it crisp for a couple of days.
• Taste and adjust. Mandarins vary widely in sweetness. If your fruit is very sweet, add an extra tablespoon of lemon juice to the reduced juice.

vi. Variations

For a meringue-topped tangerine tart, finish the set tart with Italian meringue and brown it with a blowtorch, in the manner of a lemon meringue pie. A clementine and almond tart bakes the reduced juice into a frangipane rather than a curd, closer to the almond tart. Candied tangerine slices, made by simmering thin slices in sugar syrup until translucent, make a striking decoration. Blood oranges, yuzu or a mix of tangerine and passion fruit all work in the same recipe.

For other citrus desserts on DessertCat, see the orange mousse, the British lemon posset and the Caribbean-leaning lime coconut pie.

vii. Serving & storage

Serve the tart chilled or just cool, in slices, on its own or with a spoonful of crème fraîche, which balances the sweetness with a gentle sourness. A few fresh tangerine segments or a dusting of icing sugar around the edge make an easy garnish. It is a good make-ahead dessert for winter dinners and festive meals, and its colour is particularly welcome in December and January.

Keep the tart covered in the fridge for up to 3 days; the pastry gradually softens after the first day. The curd can be made up to 4 days ahead and kept in the fridge with clingfilm pressed onto the surface — warm it gently and stir before filling the case, or spoon it in cold and smooth the top. The baked, unfilled pastry case keeps for 2 days in an airtight tin. The filled tart can be frozen for up to a month; thaw overnight in the fridge.

ix. More from French

• Orange Mousse — chilled citrus mousse
• Almond Tart — tarte aux amandes
• Pear Tart — tarte Bourdaloue
• Praline Tart — Lyon's pink tart
• Lemon Meringue Pie — curd under meringue
• Lemon Posset — British set lemon cream