Finely slice the red onion, then put in to a small bowl and cover with cold water. Leave to soak while you prepare the rest of the dish.
Cut the bread in to large dice, lay out on a baking tray or large dish and leave somewhere warm to dry out even more.
Cut the tomatoes into large dice about the same size as the bread and place in a large bowl. Add the salt and pepper, capers, white wine vinegar and 1 tbsp of olive oil. Stir to combine and leave to sit at room temperature.
Finely chop the garlic and whisk together with the remaining 1 tbsp of olive oil plus a pinch of salt. Slice the aubergine into 4 lengthways.
Heat the griddle pan on a medium-high heat. Brush the aubergine slices with the garlic oil. Cook the aubergine in the griddle pan until soft.
Remove the aubergine slices from the griddle pan and set aside, if your bread isn’t already really stale, throw the bread in to the hot pan and toast on the griddle for a couple of minutes turning regularly.
Add the toasted bread to the tomato salad. Drain the onions well and add these to the salad.
Stir everything together well so the bread absorbs all the liquid from the tomatoes. Roughly chop the basil leaves and stir into the salad, setting aside a few for garnish.
Spoon the salad on to plates. Serve topped with the griddled garlic aubergine and decorated with a few extra basil leaves.
