Getting started: Take the chicken out of the fridge 30 mins before cooking, to let it to come to room temperature.

Pour the teriyaki sauce into a bowl. Finely chop half the chilli, scraping out the seeds if you prefer less heat. Peel and grate or crush the garlic. Separate the coriander leaves and stalks. Finely chop the stalks. Trim the roots and any ragged greens off the spring onions and finely slice them, keeping the white and green parts separate. Add the chilli, garlic, coriander stalks and white spring onions to the teriyaki sauce (save the coriander leaves and green spring onions for later). Zest in the lemon and stir in the juice from 1 lemon half.

Cooking indoors: Preheat your oven to 180°C/Fan 160°C/Gas 4. Place the spatchcock chicken skin-side up in a large roasting tin. Rub the skin with a good pinch of salt and pepper and 1 tbsp olive oil. Slide the chicken into the oven and roast for 1 hr.

When the chicken has roasted for 1 hr, brush half of the teriyaki marinade evenly over the skin. Return the chicken to the oven for 10 mins, then brush with the remaining marinade. Pop the chicken back into the oven for another 5-10 mins, till cooked through, sticky and slightly charred. To check if the chicken is cooked, insert a skewer into the thickest part of the thigh. The juices should run clear. If it needs longer, return the slide back into the oven for 5-10 mins and check again.

Lift the chicken out of the tin onto a plate or board, loosely cover with foil and set aside to rest for 20 mins before carving. Top the chicken with the coriander leaves, spring onion greens, and a few slices of the remaining chilli if you like. Serve with wedges of the remaining lemon half for squeezing.

Cooking outdoors: Light your barbecue and bring the coals to a medium temperature (see our tip, overleaf, on lighting the perfect barbecue).

Lay the chicken skin-side down over the hottest part of the barbecue and cook for 4-5 mins, or till golden. Turn over and cook for another 4-5 mins. Transfer the chicken to a cooler part of the barbecue and cook, with the lid on, for 1 hr.

When the chicken has cooked for 1 hr, brush half of the teriyaki marinade evenly over the skin. Cover the barbecue and cook the chicken for 10 mins, then brush it with the remaining marinade and cover again. Barbecue the chicken for another 5-10 mins, till cooked through, sticky and slightly charred. To check if the chicken is cooked, insert a skewer into the thickest part of the thigh. The juices should run clear. If it needs a little longer, return the chicken to the barbecue for 5-10 mins before checking again.

Lift the chicken onto a plate or board, loosely cover with foil and set aside to rest for 20 mins before carving. Top the chicken with the coriander leaves, spring onion greens, and a few slices of the remaining chilli if you like. Serve with wedges of the remaining lemon half for squeezing.