For me, the best way to cook a whole chicken on the barbecue is to be safe and cook it blonde in the oven first – then finish it on the barbecue to get that crispy, golden skin and let that smoky flavour penetrate right through.
Mix all the marinade ingredients together in a large bowl and set aside. Slash the chicken across each leg about 3 or 4 times – this will allow the heat to penetrate directly into the meat and help it cook faster. Place the chicken in the marinade, rubbing the flavour all over. Cover and leave in the fridge for at least 12 hours.
Preheat the oven to 190°C/gas 5. Remove the chicken from the brine and pat it dry with kitchen towel, then place in a roasting tray. Cut a lemon in half and pop it inside the chicken’s cavity with the bay leaves from the brine. Cover with a double sheet of tin foil and roast in the oven for 1 hour, until cooked through.
Meanwhile, cut the potatoes into rough 2cm cubes and toss in a large roasting tray with a good splash of olive oil, the smashed garlic and the picked oregano. Season with sea salt and black pepper and roast alongside the chicken for about 40 minutes, or until lovely and crispy and golden.
After an hour, remove the chicken from the oven and finish on the barbecue, turning occasionally until beautifully golden and crisp all over. Make the French dressing by shaking up the mustard, extra virgin olive oil, vinegar, plus a pinch of sea salt and black pepper, in a jam jar. Add the salad greens to a serving bowl, drizzle over the dressing and toss to coat. Serve the chicken with the crispy potatoes and the salad.