Make the chermoula by roughly tearing up the herbs and placing in a food processor with all the other ingredients. Season to taste and blend to a rough paste. Smear the chermoula over both sides of the swordfish steaks.
Brush a large griddle pan or heavy frying pan with oil and heat over a high heat. Add the swordfish and cook for 1½–2 minutes on each side, until just cooked through. Serve immediately with herbed couscous.