Toss the chicken in 1 tsp sumac. Heat 1 tbsp oil in a frying pan and fry the chicken for 6-7 minutes until golden and cooked through. Add the olives and coriander.
Meanwhile, place the couscous and preserved lemons in a bowl and pour over 300ml boiling water, cover and leave for 5 minutes, fluff up with a fork. Leave to cool slightly.
Whisk together the lemon juice, remaining sumac and oil and toss into the salad. Mix in the chicken and couscous.
