In a large non-metallic dish, mix the zest and juice of 1 of the lemons with the garlic and 1½ tablespoons of oil. Add the chicken and mix to coat. Cover with clingfilm and marinate in the fridge for at least 1 hour.
Meanwhile, put the bulgar wheat in a large pan, pour over 650ml boiling water and simmer, covered, over a low heat for 15 minutes, until the liquid has absorbed. Remove from the heat and let stand for 5 minutes.
Stir through the herbs, tomatoes and onion. In a small bowl, whisk together the remaining oil with the juice and zest of the remaining lemon and the mustard and honey, then toss through the tabbouleh.
Season with freshly ground black pepper and cover until needed. Preheat the oven to 200°C, fan 180°C, gas 6. Put the chicken on a large baking tray and cook for 40-45 minutes, until cooked through with no pink remaining. If you like, you can then transfer the chicken to a hot barbecue or griddle pan and sear on both sides for a few minutes.
Warm the flatbread either on the barbecue or griddle pan for a few mins either side, or in the oven to pack instructions. Slice and serve with the chicken and the tabbouleh salad.