For the pastry, process the flour and butter with salt in a food processor into a crumbly mixture. Add little ice water and start the machine again - only add enough water so that the mixture forms a ball. Wrap the pastry in cling film or seal in a plastic container and put into the refrigerator for 30 minutes.
Roll out the pastry to fit the bottom of a 23cm cake or tart tin and press pastry 2-3cm up the sides. Put the pastry in the freezer for 10 minutes.
Preheat oven to 200 degrees C. Blind bake the pastry in the preheated oven for 15 minutes until the pastry is golden and cooked through but not brown. Allow to cool. Don't turn the oven off!
Drain the gooseberries, retaining the juice. Measure out 400ml of juice and mix it with ginger.
Spread the gooseberries on the pastry base. Mix some of the juice with cornflour until smooth and bring the remaining juice to the boil. Stir in cornflour and cook, stirring all the time with a whisk until the mixture thickens and becomes clear again. Pour over the gooseberries.
Beat the egg whites and salt with the vanilla until stiff and pour over the gooseberries. Bake immediately in the preheated oven for 10-15 minutes until the meringue is light brown and feels firm.