Grease a 30cm loose-bottomed tart tin.
Sift flour into a bowl and rub in butter until it resembles breadcrumbs.
Mix in icing sugar, ground ginger, beaten eggs, and enough cold water to form a dough.
Knead dough into a ball and roll out to line the tart tin.
Prick the base, line with foil, and chill in the fridge for 30 minutes.
Preheat oven to 150°C.
Cuts rhubarb into 5cm lengths and place in a dish with sugar and orange zest.
Bake rhubarb for 25 minutes until tender then increase oven to 190°C.
Add baking beans to the tart and bake blind for 15 minutes.
Remove foil and beans then bake for 8 minutes until golden.
Remove tin and increase oven temperature to 200°C.
Whisk egg whites to soft peaks, then gradually whisk in half the sugar.
Fold in cornflour and remaining sugar, whisking until smooth and glossy.
Fill the tart case with vertical rhubarb pieces and top with piping of meringue.
Bake for 30 minutes until the top is crispy and pale gold.
Allow the pie to cool before removing from the tin.