Heat a barbecue grill or chargrill on medium. Lightly spray the chicken with olive oil spray. Cook for 3 minutes each side or until browned and cooked through. Transfer to a plate and cover with foil. Set aside for 5 minutes to rest.
Cook tomatoes on the grill, tossing occasionally, for 5 minutes or until blistered.
Combine the tomatoes, onion, carrot, celery, rocket, lentils and half the basil leaves in a large bowl. Coarsely chop the remaining basil and place in a bowl with the lemon zest, lemon juice and oil.
Drizzle half the dressing over the salad and toss to combine.
Divide the salad and chicken among serving plates. Drizzle with remaining dressing and sprinkle with pistachio. Season with pepper to serve.