This dish is a tribute to the magnificent region of France where I come from, and one day you must make it part of one of your dinner parties!
Planning ahead: The pastry must be prepared at least 30 minutes (preferably 1 hour) in advance and refrigerated. The tart can be made up to 30 minutes prior to serving and kept warm.
For the pastry
200 g plain flour
pinch of salt (see Chef's note 1)
100 g unsalted butter, diced
1 x 55 g egg (see Chef's note2), plus 1 egg yolk extra, beaten, to brush
15 ml cold water (see Chef's note 3)
For the filling
50 g unsalted butter
450 g onions, finely sliced
4 pinches salt
2 pinches cayenne pepper
2 pinches ground nutmeg
10 g plain flour
100 ml milk, warmed
100 ml crème fraéche
3 eggs, beaten
100 g bacon lardons (see Chef's note 4)
Oven temperatures are for conventional; if using fan-forced (convection), reduce the temperature by 20˚C. | We use Australian tablespoons and cups: 1 teaspoon equals 5 ml; 1 tablespoon equals 20 ml; 1 cup equals 250 ml. | All herbs are fresh (unless specified) and cups are lightly packed. | All vegetables are medium size and peeled, unless specified. | All eggs are 55-60 g, unless specified.
Chilling time: 1 hour 30 minutes
Resting time: 10 minutes
To make the pastry using a food processor (see Chef's note 5), pulse the flour, salt, butter, egg and water for 20–30 seconds, until the dough is a sandy texture. Turn out dough onto a clean work surface, and knead into a ball for 10 seconds, until the dough comes together (see Chef's note 6).
Alternatively, to make the pastry by hand, mix together the flour and salt in a large bowl. Add the butter and using your fingertips, lightly rub and lift until mixture is a sandy texture. Make a well in the centre and add the egg and the water. Using your fingertips and small concentric circles, work the egg and water into the mixture until combined and clumping together. Using your hands, press the dough together (see Chef's note 6).
Pinch off 20–30g of the dough, tightly wrap in plastic wrap and reserve for patching up any holes. Roll remaining dough into a cylinder, cut in half and roll each portion into a 2cm-thick disc (see Chef's note 7). Wrap in plastic wrap and refrigerate.
Preheat oven to 170°C. Place a baking stone or heavy baking tray on middle rack of oven. Place the dough between two 40cm-square pieces of plastic wrap and roll out to a 3mm-thick circle (see Chef's note 8).
Place a 21cm x 2.5 cm high round tart ring on a wooden peel or heavy baking tray lined with greaseproof paper. Discard top piece of plastic wrap, then lift plastic wrap underneath, holding two corners closest to you (dough will cling to it). Lay the dough over the tart ring. Lift the edges and push into the ring, then press over the base of the tart. Ensure the dough is neatly compressed and moulded into the shape of the ring, to minimise shrinkage or collapse of the dough. Remove plastic wrap and use rolling pin to trim edges.
Using a thumb and index finger, push rim of the pastry case so the dough extends 2mm above rim of ring (see Chef's note 9). Use a fork to prick the base of the tart (see Chef's note 10). Chill for 1 hour, until firm (see Chef's note 11).
Place the tart ring on a prepared baking stone or baking tray and bake for 20 minutes. Remove from oven and brush inside of tart with extra beaten egg yolk. Bake for a further 2 minutes, to cook the egg and seal the pastry.
Meanwhile, to make the filling, cook the butter and onions in a large sauté pan over a medium heat for 15 minutes, until soft and lightly coloured. Season with salt, cayenne pepper and nutmeg to taste. Stir in the flour and cook for 5 minutes. Slowly add the milk, stirring, then the crème fraéche.
Simmer the onion mixture for 5 minutes, then remove from the heat. Stir in the beaten egg, then the bacon lardons. Return the tart case to the oven and gently pour in the filling. Bake for 30 minutes, until the base is golden brown (see Chef's note 12). Rest for 10 minutes, then slice and serve.
1 Always use the best salt with the least refining. Never use salt with anti-caking additives.
2 Buy organic or free-range eggs. They follow good husbandry practices and good ethical standards. The best-before date sets the shelf life of the egg, which is 21 days after it has been laid. Try to use fresh eggs.
3 The water adds moisture so the starch, sugar and egg binds together, allowing you to work the dough more easily and making the dough less prone to cracking.
4 To make bacon lardons, cut a 100g piece of bacon into 2mm cubes. Blanch, then sauté in a dry frying pan for 4 minutes, until lightly caramelised.
5 All my life I have tried to establish the closest possible relationship with ingredients. I thought 'by hand" was always better than 'by machine". Having tried this recipe in a food processor, pulsing the mixture together I saved time, but I had a lesser pastry. By hand you will achieve perfect shortbread quality, so I am happy to confirm that by hand is better. The dough made in the machine can be easily over-mixed, making a pastry that is too delicate and powdery.
6 If you knead the dough for too long, the ingredients will be too intimately mixed together and the dough will become elastic and retract during cooking. The pastry will also be less flaky as all the air has been removed.
7 I am sure you have done a recipe where you have balled the dough and it has taken you 10 minutes of bashing the cold dough into a flatter shape. Rolling the dough into two 2cm discs avoids all these aggravations.
8 Rolling the dough between squares of plastic wrap is a marvellous little technique. You will not need flour, which will make the pastry heavier, and your work top will be cleaner, but mostly it solves the problem of rolling a delicate dough in a warm kitchen, when it is sticking, making a real drama.
9 We do not use any dried beans to blind-bake the dough. By pushing the edge of the tart to 2mm above the rim, you are minimising the retraction of the pastry during cooking.
10 By pricking the base of the tart case, you allow and the steam generated during cooking to escape, helping to keep the case flat and level.
11 Chilling or resting the pastry before you cook it minimises any shrinkage.
12 The safest way to check the base of your tart is to use a spatula and gently lift the tart to check the colour of the base. Make sure it is a golden brown colour.