Preheat the oven to 200C (fan).
Make the marinade by adding all the ingredients into a bowl and mixing together.
Spatchcock the chicken. Use scissors or a sharp knife to cut down either side of the spine of the chicken. Remove the spine completely. Flip it over, then press down to flatten it.
Use a sharp knife to slash the chicken all over.
Cut the potatoes into halves and the bigger ones into quarters then add them into a large baking dish.
Lay the chicken over the top of the potatoes, then pour the marinade over the top, letting it drizzle into the potatoes. Rub the marinade all over the chicken and into the cuts. Toss the potatoes around to coat them too.
Bake it for 50 minutes.
Take it out from the oven and spoon over any juices over the chicken.
Add the tomatoes and peppers and toss together with the potatoes.
Put it back into the oven for a further 10 minutes, then it’s ready to enjoy.