Harissa Chicken with Leeks and Garlic Mash

So straightforward is the chicken that if I were writing a cookbook I would be embarassed to include this as a recipe. That said, the recipe comes from Moro by Sam & Sam Clark (a book I do recommend):

Smear harissa on a chicken. Put it in a roasting tray, sprinkle with olive oil and roast it. An hour at 200C should put you in the ballpark. Baste with a little more oil after half an hour.

The leeks are my own invention:

Cut the leeks into 1cm clices. Melt some butter in a frying pan and add the leeks. Add 2 tsp harissa. Splash in 2 tbsp sherry vinegar and a little salt. Cook until the leeks are just beginning to soften.

The garlic mash doesn't deserve instructions. It's obvious.

Use the oil / juice from the bottom of the roasting pan as gravy for the chicken and potatoes.