Heat the oil in a non-stick pan, add the chicken and fry for 2 minutes on each side until browned.
Place the couscous in an ovenproof dish. Mix together with the stock, red onion, red pepper, parsley, lemon zest and juice, pour over the couscous and stir.
On top of this, place the chicken then spoon over the pesto and season to taste.
Cover the dish with foil and bake for 20 minutes.
Once cooked, fluff up the couscous with a fork. Serve hot or cold.