1.In a large frying pan, pour olive oil to 3cm deep. Heat over moderate heat (oil is ready when a cube of bread crisps quickly without absorbing oil). Shallow-fry bread, in batches, 1-2 minutes or until golden and crisp. Using a slotted spoon, transfer to paper towels. Top up oil between batches if necessary.
2.In a large serving bowl, combine bread, cucumber, tomato, onion and basil. Drizzle extra oil and vinegar over salad. Season with salt. Toss to combine, then serve at once.