Begin the day before you want to make the pie. For the curds, bring the milk to the boil in a pan. Add the lemon juice and stir well - the mixture will curdle quite quickly. Remove from the heat and allow to cool, then pour into a muslin-lined sieve placed over a bowl and leave overnight to strain until solid. Refrigerate the solid curds once separated - discard any liquid.
The next day, for the pastry, sift the flour and salt into a mixing bowl. Add the butter and lard and rub together until the mixture resembles fine breadcrumbs. Add the water and stir until the mixture comes together, then turn out onto a lightly floured work surface and knead briefly until smooth. Wrap the dough in cling film and place in the fridge for 30 minutes to rest.
Remove the dough from the fridge and roll out to 0.5cm/¼in thick. Line a deep 20cm/8in loose-bottomed tart tin with the pastry, prick the base all over with a fork and place into the fridge to rest for ten minutes.
Preheat the oven to 200C/400F/Gas 6.
Line the pastry case with baking paper and fill with rice or baking beans. Transfer to the oven and bake for 15 minutes. Remove the baking paper and rice or beans and return to the oven for five minutes, or until lightly golden.
To make the pie, place the softened butter into a bowl, add the rosewater and mix well. Add the solid curds and the beaten eggs to the bowl and stir well. Add the currants and mix thoroughly.
Pour the mixture into the pastry case and bake for 20-30 minutes, or until the filling is set and lightly golden. Remove from the oven and leave to cool.
To serve, remove the pie from the tin, cut into wedges and place onto serving plates.
