Sous-vide Lemon Tart

This is based on the excellent Chef Steps Lemon Curd for the pie filling.

Ingredients:

• 230g plain flour
• 50g butter, cut into small cubes
• 80g baking block (70% fat)
• 75g icing sugar
• 7 yolks from large eggs
• 1 tsp citric acid
• a pinch of salt
• 175g golden caster sugar
• 200g butter
• 4 lemons, juiced and zested

Method:

1. Mix the flour, icing sugar, 50g of butter and baking block in a large bowl. Use your finger tips to rub the fat into the flour until it resembles bread crumbs.
2. Put one of the yolks into the mixture and mix into a ball. If it doesn't stick then add a few drops of water, but try to keep it as dry as possible yet still forming a bowl.
3. Wrap in cling film and place in the fridge for at least 30 minutes.
4. Pre-heat the oven to 200 degrees and put on the sous-vide at 75 degrees celsius.
5. Grease a 20cm pie tin with some butter.
6. Remove the pastry from fridge, roll out into about a 30cm circle and then carefully lift into the pie tin.
7. Trim off any excess pasty.
8. Return pastry to the fridge again for another 30 minutes.
9. While waiting for the pastry to chill again, mix the remaining 6 egg yolks, citric acid, salt, lemon juice and zest, 200g butter and caster sugar in a sous-vide bag.
10. Seal carefully with a vacuum sealer and place in the water bath for an hour.
11. While that's cooking, bake the pastry for 15 minutes, using a layer of foil or baking parchment with baking beans/rice to stop the sides collapsing.
12. Let the pastry case cool on the side while waiting for the curd to finish cooking.
13. When the hour is up, pour the curd into a tall beaker and use a hand/immersion blender to mix the curd into a consistent texture. This introduces far fewer bubbles than a normal blender, but you'll still get a couple. Tapping the beaker firmly on the work top can help burst them.
14. Pour the curd into the cooled pastry case and the place the finished pie in the fridge for at least a couple of hours to let the curd set.

Fills a 20cm pie tin.