Crank your oven to 250C (480F) (don't worry the food won't be in there long enough to burn).

Spread frozen beans (don't defrost) over a large rimmed baking tray so that everything is sitting in a single layer. I line mine with baking paper so it's easier to clean. Place chicken next to the beans spreading the chicken as flat as possible. Scatter a pinch of salt over the chicken.

Pop in the oven (don't wait for it to heat up completely - get it in as soon as possible - that's part of the plan). Set your timer for 12 minutes.

When the timer goes check to make sure the chicken is no longer pink. If it needs longer pop back in the oven for another few minutes. When the chicken is cooked, smear harissa over the chicken. Serve straight away.