Mix the cumin, coriander, paprika, turmeric and ginger in a large bowl. Add the garlic and lemon zest and finely grate in the onion.
Mix well and add the sea bream, coating all over with the spice mix. Cover and place in the fridge for at least an hour (or overnight is best).
Put the couscous, sultanas and lemon juice in a bowl, heat the kettle and just cover with boiling water. Cover the bowl with a plate.
Heat the oil in a large frying pan and turn the grill to high. Place the bream fillets in the pan skin side down and cook for 2 minutes then put fillets, still in the frying pan, under the grill and cook for 3 more minutes.
Mix the couscous with a fork to break it up and divide it between four plates. Top with the grilled fish and sprinkle with coriander.