First make the pastry. Put the flour, salt, caster sugar and butter in the bowl of a food processor and mix together at the lowest setting until it looks like fine breadcrumbs. Add the egg and the water. The mixture should soon form into a pliable ball. If necessary add a very small amount more water, but always underestimate and go for a little at a time. Remove the pastry from the food processor bowl, roll into a ball and flatten slightly to a thick disc shape (this makes it easier to roll out later). Wrap in clingfilm and place in the pastry in the refridgerator for 30 minutes.
Very gently toss the aubergine and courgette strips in a bowl with 2 tbsp of the olive oil.
Heat a ridged grill pan until it is very hot then place strips of the aubergine and zucchini across the ridges. You will need to do this in batches, being careful not to crowd the pan. Don’t be tempted to move the strips, other than to turn them over, while they are cooking. When they have charred lines on each side they are ready. Drain on kitchen paper and pat dry to remove excess oil.
Pre-heat the oven to 150?C (300?F, gas no.2).
Heat the olive oil in a frying pan over a medium heat, add the onions and cook until soft, which will take around 5 minutes or so. Add the garlic and cook for a further minute, stirring to ensure the garlic does not burn, then add the tomatoes, the basil and the oregano. Lower the heat and simmer, stirring frequently, for a further 10 minutes, by which time you will have a fairly thick, rich sauce. Remove from the heat and leave to cool.
Roll out the pastry and line a greased flan case. Trim the pastry so that there is a slight overhang of about 1 cm. Any unused pastry can be frozen for use in the future. Prick the base and sides with a fork and line the flan case with parchment and baking stones or beans. Bake the flan casing blind in the preheated oven for 10 minutes. Remove from the oven, leave to cool slightly and then remove the parchment and baking beans. The edges of the flan will have shrunk slightly, but now you can trim them neatly to the height of the flan dish with a sharp knife.
Now you need to assemble the tart, which should be done in layers, as follows. Put a couple of tablespoons of the tomato sauce in the base of the tart and spread evenly with the back of a spoon. Scatter the chargrilled aubergine evenly across the top. Now add another two tablespoons of the sauce, spread evenly and scatter over the sliced peppers. Add another two tablespoons of the sauce, spread evenly and scatter the zucchini slices evenly over the top. Cover the zucchini with any remaining sauce, then scatter the olives and capers over the top. Finally, sprinkle the mozarella and Parmesan evenly over the top.
Bake in the oven for around 45 minutes, or until the top is beginning to turn a golden brown. Remove from the oven. If serving hot, the tart rest for a few minutes before slicing.