Put all ingredients except chicken in a bowl and mix.
Add chicken, coat in marinade, and marinate overnight.
Preheat oven to 180 degrees.
Heat a heavy-based pan, seal chicken skin-side down, then transfer to roasting tray to cook in oven 15 minutes.
Rest in a warm place for 5 minutes. Slice and serve on warm pearl couscous with tahini yoghurt.