Place flours and butter into the bowl of a food processor. Process until mixture resembles fine breadcrumbs. Add egg yolk and water and process until mixture just comes together. Turn out onto a lightly floured work surface and knead gently until smooth. Shape into a disc, cover with plastic wrap and place into the fridge to rest for 30 minutes.
Preheat oven to 200℃ (180℃ fan forced). Roll out the pastry on a lightly floured surface to a 3mm-thick disc. Line a 24cm (base measurement) loose-bottom fluted tart tin with the pastry. Use a small sharp knife (or a rolling pin) to trim the edges. Discard excess pastry. Prick the base all over with a fork. Place in the freezer for 15 minutes to rest.
Line the pastry with baking paper and fill with pastry weights or rice. Bake for 10 minutes. Remove the paper and weights and bake for further 10 minutes or until light golden. Remove from oven and allow to cool completely. Reduce oven temperature to 180°C (160℃ fan forced).