This tart combines delicious, crisp pastry with smooth lemon filling. It can be served warm or cold.
Preheat the oven to 200C/390F/Gas 6.
For the pastry, place the flour, butter and icing sugar into a food processor. Blend until the mixture looks like breadcrumbs, then add the egg and water. Blend again until it forms a ball. Roll out the pastry very thinly on a floured work surface until just a little bigger than the size of a 28cm/11 deep, loose-bottomed tart. Line the tart tin, letting the extra pastry overhang over the sides of the tin. Place on a baking sheet and then chill in the fridge for 30 minutes.
To bake the pastry blind, line the tin with greaseproof pastry and fill with baking beans. Blind bake for 15 minutes in the preheated oven until pale golden-brown. Remove from the oven and remove the baking beans and paper. Carefully trim the excess pastry off around the sides using a sharp knife. Return the empty pastry shell to the oven for another 10-12 minutes or until it is completely dry. Set aside to cool.
Reduce the temperature of the oven to 180C/350F/Gas 4
Measure all of the filling ingredients into a bowl and whisk together until smooth. Carefully pour the filling mixture into the cooled baked pastry case.
Carefully transfer to the oven and bake for about 40-45 minutes or until just set but with a slight wobble in the middle. The filling will be soufflé like when it comes out of the oven, but will sink down when it has cooled down.
Leave to cool a little or completely then remove from the tin, transfer to a serving plate and dust with icing sugar to serve.