Preheat oven to 400°F (200°C).

In a small bowl, combine harissa paste and olive oil. Season salmon fillets with salt and pepper, then spread the harissa mixture evenly over the top of each fillet.

Place salmon on a baking sheet lined with parchment paper and bake for 12-15 minutes, or until cooked through and flaky.

While salmon bakes, prepare couscous: In a medium bowl, combine dry couscous with boiling water or broth. Cover and let stand for 5 minutes, then fluff with a fork.

Serve the harissa salmon immediately over the prepared couscous, garnished with fresh parsley and lemon wedges if desired.