Sieve the flour and salt into a large mixing bowl, then cut the butter and fat into the flour and rub in until the mixture resembles fine breadcrumbs. Stir in the sugar. Mix the egg yolk with 3-4 T of water. Sprinkle over the top of the crumbled mixture. Mix with a broad bladed knife to form a stiff ball. Work only long enough to form a ball. Leave the pastry to rest in the refrigerator for about 30 minutes before using.
The food processor is a most convenient way to make pastry crust. Success, however, depends on careful processing to ensure the dough is not overworked.
Pastry freezes well and can therefore be prepared in advance.
Prepare the pastry. Divide into two and roll one piece 1 1/2 inches larger than an ovenproof pie plate. Line the plate with the pastry and cut off the excess.
Brush the pastry rim with lightly beaten egg white (reserved from making the pastry) and lay the pastry trimmings on top.
Peel, core and thinly slice the apples. Arrange alternate layers of apples and sugar in the center of the plate with cloves.
Roll out the second piece of pastry just large enough to cover the pie. Brush pastry rim with egg white and and cover the pie with the pastry lid. Press the edges firmly together to seal and flute to decorate.
Brush the pie with the remaining egg white and sprinkle with castor sugar. Bake in a 400F (200C or Gas Mark 6) preheated oven for 10 minutes, then reduce the temperature to 350F (180C or Gas Mark 4) and bake further for 20-30 minutes or until the apples are tender and the pastry is pale gold in color. Sprinkle with more castor sugar and serve hot or sold with whipped cream.
For Rhubarb Tart, use 2-3 lb rhubarb cut in 3/4 inch lengths, tossed in 2 T cornflour.
For Apple and Blackberry Pie, use 2 lb of apples and 1 lb of blackberries.