Preheat the oven to 170°C/Fan 150°C/Gas 3.
Spread the sourdough croutons over a baking sheet and bake in the hot oven until golden, 10–15 minutes. Leave to cook as you make the salad.
Place the chopped tomatoes in a large bowl, add all the other ingredients including the sourdough croutons, season with salt and pepper and toss together.
Leave to sit for 10 minutes before serving.