Tip the couscous into a large heatproof bowl and pour over 400ml boiling water. Cover with cling film and leave to stand for 8-10 mins while you cook the fish.
Heat a large, non-stick frying pan over a medium heat. Brush the salmon fillets with olive oil and fry for 5 mins on one side or until opaque halfway up the side of the fillet. Flip the fillets over carefully and cook for another 1-2 mins or until cooked through, then remove from the heat.
Mix the tahini with the lemon juice and a splash of water to make a sauce.
Drain any excess water from the couscous and tip into a bowl, adding the cucumber, pomegranate seeds and parsley. Serve the salmon on top of the couscous, with lemon wedges on the side and the tahini sauce poured over or served alongside.