Combine the olive oil, lemon juice and lemon pepper in a bowl. Season with salt and whisk to combine. Stir 2 tablespoons into the basil pesto, cover and set the pesto dressing aside.
Place the chicken onto a large plate. Spoon over the remaining lemon pepper mixture, turn to coat both sides. Cover and refrigerate for 15 minutes if time permits.
Preheat a barbecue plate or chargrill on medium high until hot. Remove the chicken from the marinade, discarding the marinade. Barbecue the chicken for 4-5 minutes each side or until lightly charred and cooked through. Remove to a tray. Cover and stand for 5 minutes.
Meanwhile, combine the rocket, mango, lentils, tomatoes and feta on a large serving platter. Cut the chicken in half crossways and arrange over the salad. Spoon over the basil dressing, scatter with basil leaves, season and serve with crusty baguette.