Blend the flour and salt together. With two knives, a pastry cutter, or your fingertips, cut or rub half of the lard into the flour/salt mixture until it looks like bread crumbs. Cut in the remainder until the largest pieces are the size of peas.
Beat the lemon juice and egg into the cold water and sprinkle this over the flour/lard mixture, blending it in lightly with a fork until the dough just holds together.
Press the dough into two flattened disks, wrap in plastic wrap and refrigerate while you make the filling. (This can be done ahead of time.)
Preheat your oven to 400°F.
Mix the sugar, flour and salt in a medium-sized mixing bowl. Blend in the lemon rind and lemon juice.
Break the egg into the milk in a small bowl and beat until light. Blend this into the lemon mixture. Fold in the butter last.
Roll out the pie crust and fit into a 9-inch pie pan.
Pour in the filling and cover with a top crust. Moisten the edge of the bottom crust, tuck the edge of the top crust underneath the bottom crust, and flute the edges with a fork or with your fingers.
Prick holes or cut a design in the top piece of dough with a knife.
If you have any pastry trimmings left over, you can cut out small shapes (maybe lemons?) and attach them artistically to the top crust with a bit of water. To make them a bit more visible, brush them with a wash made of an egg beaten with a tablespoon of
Bake for 30 to 35 minutes. Remove from oven and let cool to room temperature, or just slightly warm, before serving.