Preheat the oven to 220°C/fan 200°C/425°F/Gas 7. Line a baking dish with baking paper.
Arrange the fruit cut-side up in the lined baking dish and sprinkle with 1 tablespoon of the vinegar, along with the honey or sugar. Roast for about 15–20 minutes, or until the tops of the fruit begin to bubble and char at the edges, and syrupy juices form in the bottom of the baking dish.
Remove from the oven and leave to cool slightly.
Meanwhile, in a separate baking dish, mix the bread with a good measure of olive oil and a good pinch of salt. Bake for about 8–10 minutes in the hot oven, until the bread is nicely toasted.
In a small bowl, mix together the 2 tablespoons of olive oil and the remaining vinegar, along with any juices left over from roasting the fruit, and the chilli flakes, if using. Season with salt and pepper.
On a large serving dish, arrange the peaches (or other fruit) and toasted bread and pour over the dressing. Add the mozzarella and basil. Drizzle with a little more olive oil and serve.