To make the pastry, sieve the flour and salt into a large bowl. Cut the butter into small cubes and rub into the mixture until it looks like crumbs. Add the sugar and mix in with a fork. Drizzle in the egg yolk and stir in with a knife.
Roll out the pastry into a round and cover with cling film and refrigerate for at leat 45 minutes.
Preheat the oven to 190°C (Gas 5). Grease a 23cm(9inch) shallow tart tin with a removable base with a little butter.
Remove the pastry from the fridge and place between two pieces of cling film (slighter larger than your tin). Roll out to approx 3mm thick and make sure and keep it round. Remove the top layer of cling film and place upside down on your tin. Press into the edges and then cut excess pastry from the tin and remove the top layer of cling film. Pop pastry into the freezer for 10 minutes.
Remove the pastry from the freezer and cover with greaseproof paper and fill with baking beans. Place in the oven for 15-20 minutes until the pastry feels dry. Remove the paper and beans and brush with the egg white to seal and return to the oven for 2 minutes, remove and set aside.
Turn down the heat of the oven to 120°C(gas mark ½).
To make the filling place the eggs and sugar in an electric mixer and beat for approximately 10 minutes until pale and creamy. Add the lemon juice and zest and beat for a further 5 minutes. Add cream and beat for a further 5 minutes.
Carefully pour the mixture into the tin with the pastry. Return to the oven and bake for 25-35 minutes until the filling has set in the centre.
Remove from the oven and allow to cool for about 10-15 minutes before transferring to a plate.
When cool dredge with icing sugar and cut into slices to serve.
To make the coulis, blend the raspberries, icing sugar and lemon juice in a food processor and pass through a fine sieve.
To serve place some raspberry coulis on a plate and place a slice of tart on top and lightly sprinkle more icing sugar on the edges of the plate.