Fire up the barbeque and wait till the coals are medium hot.
In a small bowl, mix together the harissa, orange juice, olive oil, pomegranate molasses and salt and set aside.
Brush a little oil on the grill, then place the chicken breast side up on the coolest part of the barbeque. Make sure that there aren’t any coals directly under the chicken, you are trying to roast it, so it wants indirect heat. Remember, your barbecue is becoming an oven. After you have browned the skin, wrap the chicken in silver foil.
Then close the barbeque lid and cook for 80-90 minutes. The time depends on your barbeque so do check that the chicken juices run clear before taking it off the barbeque. Do turn the chicken half way through so it cooks evenly on all sides.
Let the chicken rest for about 10 minutes before carving it.
Notes - If cooking in an oven then roast the chicken for 30- 35 minutes at fan-assisted 180C / 200C / 400F / gas 6.