Step 1
To make the pastry, sift the flour and salt into a large bowl. Using your fingertips, rub in the Trex until the mixture looks like fine crumbs. Stir in 2 tbsp beaten egg and just enough chilled water to make a soft, but not sticky, dough. Knead lightly until smooth, then wrap and chill for 10 minutes.

Step 2
Meanwhile, in a large bowl, mix together the apples, sugar, lemon juice, sultanas and cinnamon.

Step 3
Preheat the oven to 200°C/fan oven 180°C/Gas Mark 6.

Step 4
Roll out the pastry on a lightly floured surface into a circle about 38cm (15in) in diameter. Transfer to a baking sheet — the pastry will overlap the sheet at this stage. Brush the surface of the pastry with beaten egg.

Step 5
Pile the apple mixture onto the pastry, leaving a border of about 10cm (4in) around the edge. Fold the pastry edge over the filling, tucking, overlapping and sealing it to make a freeform tart. Brush with beaten egg.

Step 6
Bake for about 25 minutes, until the pastry is crisp and golden. Serve warm or cold, with single cream, ice cream or custard.