Gird your jowls, because this is lemony. I find that lemon desserts can be so disappointingly sweet, but this lives up to its name. This is a combination of two of my favourite desserts, and it's a union that is most holy.
You may notice that in the recipe I weigh all of the liquids - this isn't a typo. I find it far more accurate to weigh absolutely everything.
Ingredients - serves 8-10
For the pastry
- 125g unsalted butter, softened
- 50g caster sugar
- Zest of 1 lemon
- 200g plain flour
- 2g fine salt
- 1 large egg
For the lemon curd and top
- 275g lemon juice (from about 4 large lemons)
- 125g unsalted butter, diced
- Zest of 1 lemon
- 3 large egg yolks
- 200g caster sugar
- 25g cornflour
- 2 tbsp Demerara sugar
- 20cm tart ring/fluted tart tin
- Baking sheet
- Baking paper
- Baking beans/rice
- Chef's blowtorch/hot grill
For the pastry, put the butter, sugar and lemon zest into a bowl and beat until pale and fluffy - treat this as though you were making a cake. It may seem bizarre to warm the butter for pastry, but trust me, this is the best sweet paste I have ever made. When the butter and sugar are well combined, add the flour and cut that in using a butter knife or dough scraper, until the mixture resembles damp, coarse breadcrumbs. Beat the egg in a small bowl, then add it to the flour mixture and cut that in until the mixture starts to clump together in large boulders. Plonk the pastry down onto the worktop, knead very briefly until it just comes together, then wrap in cling and flatten into a disc. Pop into the fridge and chill for at least an hour.
WARNING: the pastry will be very soft, but that's normal. Just work quickly and get it in that cling without poking it too much.
Preheat the oven to 200C/180C fan/gas mark 6.
When the pastry has chilled, dust the worktop liberally with flour. Roll the pastry, turning it 90 degrees after every few turns, into a disc that's slightly larger than the tart ring/tin. Set the ring/tin onto the baking sheet, then line with the pastry. Make sure you press the pastry into the corners of the ring/tin so that the sides are perfectly upright - I leave the surplus pastry hanging over the edge until baked. Prick the base of the pastry repeatedly with a fork. Rip off a large piece of baking paper, scrunch it up, then unravel it and line the pastry case with it, then fill that with baking beans.
Bake the pastry case for 15 minutes with the paper and beans, then remove the paper and beans and bake for a further 15 minutes. When the pastry case has cooled, saw off the overhanging surplus with a serrated knife.
Only when the pastry case is baked and has cooled should you start on the filling.
For the curd, put the lemon juice, butter, zest and half of the sugar into a medium saucepan. Put the egg yolks into a mixing bowl and whisk, with the remaining sugar, until slightly aerated - about a minute. Add the cornflour and whisk that in too. Bring the pan of lemon juice to a boil, ensuring the butter melts in it, then pour the lemon juice onto the egg mixture while you whisk constantly. When well combined, pour the mixture back into the pan - off the heat - then return the pan to a high heat and whisk constantly. If you stop whisking you'll end up with a scrambled mess, so while the pan is on the heat you've got to whisk. When the mixture starts to bubble, continue whisking for a minute, then pour it straight into the baked pastry case. Don't poke it or mess with it, let gravity do its job and the curd will flatten. Refrigerate for at least 4 hours, though overnight is much better.
When you're ready to serve the tart remove it from the fridge and sprinkle the Demerara sugar over the top as evenly as possible. If you own a decent chef's blowtorch, torch the top until the sugar melts and burns in a mottled, almost giraffe-print pattern. If you haven't got a chef's blowtorch, preheat the grill to high then set the tart underneath - do not take your eyes off it, as it could burn in a heartbeat. Serve.