Tear the bread into bite-sized pieces. Place them on a baking tray, sprinkle with half of the oil and grill them until golden brown.
Transfer the croutons to a large serving dish.
Wash the vegetables. Cut the cucumber in half lengthwise, then slice half a cm thick.
Halve the tomatoes and slice the spring onions.
Add the vegetables to the croutons. Toss well.
Tear the mozzarella into bite-sized pieces and add to salad. Season with salt and pepper, sprinkle with the remaining oil, lemon juice and the basil leaves. Toss and serve.