Put the flour, almonds, icing sugar, salt and vanilla in a large bowl and mix to combine.
Add the butter and rub together using your fingertips, until the mixture resembles breadcrumbs.
Add the egg yolk and mix together just until the dough comes together. If the pastry isn't coming together in a uniform mass, add the water and mix until it starts to come together.
Turn the dough onto a lightly floured work surface and gently knead it into a smooth uniform dough.
Shape into a ball and wrap in cling-film, place the pastry in the fridge for at least 1 hour.
To make the lemon cream, put the lemon juice, eggs, yolks and sugar in a large pan over a medium heat. Stir the mixture constantly until it reaches 80C on an instant-read thermometer.
Pour the lemon mixture through a sieve into a medium bowl and leave to cool for around 10 minutes.
Add the butter a few pieces at a time and blend the mixture using a hand blender. Keep adding the butter and mixing it, until all of the butter is incorporated and the mixture has thickened up.
Press a piece of cling-film to the surface of the cream and place it in the fridge to chill for a couple of hours.
Preheat the oven to 180C (160C Fan)/gas 4 and roll out the pastry on a lightly floured surface until it is about 2-3mm thick and will line a 23cm tin.
Trim off the excess pastry and put the tart in the fridge for 30 minutes.
Line the tart shell with a layer of baking parchment and fill with baking beans. bake for 25 minutes then remove the parchment and the beans and bake for a further 10 minutes, or until the pastry is golden.
Leave to cool completely before giving the lemon cream a stir and spreading it onto the base of the tart, smoothing it into an even layer.
Put the tart in the fridge to chill and make the meringue. Whisk the egg whites in a clean bowl of an electric mixer.
Place the sugar, glucose and water in a saucepan over a medium heat and boil until it reaches 121C.
Gently pour the boiling syrup into the meringue and have the whites whisking on a slow speed while this is happening.
After all the syrup has been added, increase the speed to maximum and whisk the egg whites until they are cool to the touch.
When the meringue is ready, either pipe it in a spiral on top of the lemon cream or smooth it on with a palette knife.
Using a chef's blowtorch, cook the top of the meringue. You can then serve the lemon meringue pie immediately or store it in an airtight container.
It's not advised to store this in the fridge as the pastry will become soft and the meringue will break down.