Step 1
Sift the flour and salt into a large bowl. Add the Trex and rub in with your fingertips until the mixture looks like fine crumbs. Stir in just enough chilled water to make a soft, but not sticky dough. Knead for a few moments, then wrap and chill for 10-20 minutes.
Step 2
Preheat the oven to 200°C/fan oven 180°C/Gas Mark 6. Roll out the pastry on a lightly floured surface and use it to line a 20x30cm (8x12in) oblong tart tin. Line with foil or greaseproof paper and baking beans and bake ‘blind’ (i.e. without a filling) for 15 minutes.
Step 3
Take the flan from the oven and remove the foil or paper and baking beans. Reduce the oven temperature to 180°C/fan oven 160°C/Gas Mark 4.
Step 4
Put the spinach into a large colander and pour a kettleful of boiling water over it to wilt the leaves. Run cold water over it, then squeeze the spinach with your hands to remove the excess water.
Step 5
Tear the peppers into strips and arrange them in the pastry case with the spinach and mozzarella cheese. Beat together the eggs and crème fraiche. Season. Pour into the flan case, then bake for 30-35 minutes, until set. Serve warm or cold, garnished with basil.