For the aubergines, preheat the grill to high.
Dredge the aubergine slices in the flour, then dip into the beaten egg.
Heat a frying pan until hot and add the olive oil.
Add the aubergine slices and fry, turning once, until golden-brown on both sides. Carefully remove each slice of aubergine and place onto kitchen paper and set to one side to drain.
Transfer the aubergines onto an ovenproof tray and top with the chopped mozzarella and grated parmesan.
Season with salt and freshly ground black pepper and place under the grill to cook until the topping is golden-brown and bubbling.
For the tomato sauce, heat a pan until hot and add the olive oil, onion and garlic and fry for 4-5 minutes.
Add the tomatoes and bring to the boil, then add the oregano, reduce the heat and simmer for 10-15 minutes. Halfway through the cooking add the basil leaves.
Season, to taste, with salt and freshly ground black pepper and place into a food processor. Allow to cool for a couple of minutes, then blend until smooth.
For the courgette flowers, heat a deep heavy-bottomed pan two-thirds filled with vegetable oil until a breadcrumb sizzles and turns brown when dropped into it. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Sieve the flour, cornflour and salt into a bowl and add the sparkling water. Stir to combine very briefly, until the batter just comes together, leaving any lumps.
Dip the courgette flowers into the batter and turn to coat fully, then carefully place into the hot oil. Deep-fry on each side until just golden and crisp. Remove from the pan with a slotted spoon and drain onto kitchen paper.
To serve, spoon some tomato sauce onto each plate and top with some grilled aubergine slices. Garnish with a battered courgette flower and serve.