Preheat the oven to 180°C/gas mark 4. Toss the ciabatta cubes with the olive oil and season well, then put on a baking sheet and bake for 12-15 minutes until golden brown.
Meanwhile, roughly chop the tomatoes and combine in a large bowl with the cucumber and red onion.
CHILDREN: Combine the virgin olive oil, vinegar, mustard, garlic and basil to make the dressing.
CHILDREN: Toss the ciabatta croutons, dressing and mozzarella through the salad.
Cover and allow to sit at room temperature for at least half an hour so the flavours can combine before serving.