Heat the oil in a large frying pan or cast iron pot. Season the chicken pieces with the salt and pepper, then place in the hot pan and brown the meat all over on a high heat (about 6-7 minutes).
Turn the heat down to medium and add the onion to the pan with the chicken, cook for 3-4 minutes, stirring occasionally until the onion starts to soften.
Add the garlic, cumin, paprika and celery salt and stir into the onions. Pour in the hot stock and bring to the boil, place a lid or some foil on the pan and simmer for 10 minutes.
Take the lid off and take out the largest piece of chicken, make a cut into the fattest piece of the meat and check it's no longer pink inside. If it's still pink cook for a further 5 minutes and check again. Once cooked through, pour in half the lemon juice and add the chopped peppers to the pan. Pour the couscous into the stock - making sure it's all submerged and evenly distributed, then place the lid or foil back on and turn the heat down to very low. Cook for 5 minutes, then turn off the heat.
Take off the lid and fluff up the couscous with a fork. Sprinkle on the crumbled feta, lemon zest, pomegranate seeds, chopped spring onions and tomato slices, then serve with the remaining lemon juice.
Note: Any leftovers can be cooled, covered and refrigerated - serve cold for lunch the next day!.Nutritional Information is per serving.