In a bowl combine the chickpeas, capsicum, tuna, tomatoes and onion. Mix together the olive oil and balsamic vinegar and add it to the chickpea and tuna mix. Arrange the rocket on individual plates and top with the chickpea mix and shaved parmesan. Season with cracked pepper and serve.
Note: make a practice of draining and rinsing canned chickpeas in fresh water to reduce the salt content.