Step 1
Sift the flour and salt into a large mixing bowl. Add the Trex, rubbing it in with your fingertips until the mixture looks like fine breadcrumbs. Add the chilled water and mix it in with a round-bladed knife until the pastry clings together. Use your hand to form the dough into a ball – it should be firm enough to roll out without cracking. Wrap the pastry in cling film and chill for 10 minutes.

Step 2
Preheat the oven to 200°C/fan oven 180°C/Gas Mark 6. Grease 2 baking sheets with a little Trex.

Step 3
Roll out the pastry on a lightly floured surface into a large rectangle and cut into three 10cm (4in) wide strips.

Step 4
Mix the sausage-meat, spring onions, parsley and seasoning together. Divide into 3 equal pieces, then roll these into 3 lengths, placing one onto each strip of pastry. Brush the pastry edges with the glaze.

Step 5
Fold the pastry strips in half, lengthwise, to enclose the sausage-meat, pressing the cut edges together firmly to seal them. Brush with the glaze. Cut the sausage rolls into suitable lengths, arrange on the baking sheets, then prick the tops with a fork, or slash them 2-3 times with a sharp knife.

Step 6
Bake for 18-20 minutes, until golden brown. Serve hot or cold.