1. Preheat the oven to 200°C.
2. Clean the chicken, remove all the innards and dry using a kitchen towel. Ensure to remove as much moisture from the surface as possible. Keep aside.
3. Prepare a baking tray by placing the onions, carrots, celery,pepper corns and crushed garlic pods on it. The vegetables will form a base on which the whole chicken will be placed. Keep aside.
4. In a large mixing bowl combine the oil, butter, lemon juice, tandoori masala and salt to make a rub.
5. Place the chicken in the large bowl with the tandoori-butter rub and massage it onto and into the chicken. Ensure the mixture completely coats all parts of the chicken including the cavity.
6. Pierce two lemons with a skewer alternated by the bay leaves and stuff them into the cavity. Tie the chicken legs together using a trussing thread (twine). This ensures the chicken holds its shape and that the juices stay inside the cavity.
7. Place the chicken on top of the vegetables in the baking tray, cover the tray with aluminium foil and bake for 35-40 minutes.
8. Then remove the aluminium foil,change the oven setting to a medi um grill. Grill till the chicken gets a crisp caramelized skin. This should take between 5-10 minutes.
9. Remove from oven. Let it rest for 10 minutes.
10. Transfer to serving platter along with vegetables.
11. Carve and serve.