In a large bowl, squeeze half a lemon for each 2 fillets. Add 1 tablespoon olive oil, black pepper, a little sea salt and 1 tablespoon fennel seeds. Stir well to mix and blend flavours. Add fish fillets and marinate for 5-10 minutes.
Line grill pan with foil. Preheat grill, place fish fillets skin or outer side up on pan, spoon over the remaining marinade. Grill on high for 5 minutes, until skin is shrinking and crinkly or fish is starting to turn opaque.
Switch off grill and leave fish to stand while preparing couscous.
Finely dice sweet potato, peppers, and onions.
Mix with enough extra virgin olive to coat. Pour onto a parchment lined baking tray, and roast at 200-220 C for about 15 min or until soft.
Preheat a large saucepan, add 1 tablespoon oil, add the dry couscous and stir well to coat evenly.
Pour over boiling water to 1 inch above the couscous, cover pan and cook for 10 min until tender, drain and mix in the vegetables, black pepper and salt to taste. Add 2 tablespoons dried parsley and stir to incorporate.
Remove grill pan from grill and reheat grill, turn fish fillets over in the grill pan.
In the original marinade bowl, squeeze the second lemon half, add 1 tablespoon olive oil, black pepper, 1 tablespoon fennel seeds and mix well. Spoon over the fish fillets.
Return fish to the glowing grill for 3-4 minutes until hot and just tinged with colour at the tail end.
Pour couscous mixture onto a large serving platter and flatten in the centre. Place fish fillets on the couscous and garnish with fresh parsley or dill sprigs. Serve hot or warm.