1. Step 1

   For the chermoula, process the garlic, onion, herbs, spices and lemon juice in a food processor, gradually adding enough of the oil to form a paste. Spread the paste over the fish, then cover and refrigerate while you make the couscous.

2. Step 2

   Place the couscous in a heatproof bowl and pour over the hot stock. Cover and stand for 5 minutes, then fluff the grains with a fork. Stir in the herbs, garlic, nuts, chickpeas and lemon juice. Season to taste and set aside.

3. Step 3

   Preheat a barbecue or large frypan to medium-high heat. Cook the fish for 2-3 minutes each side until just cooked.

4. Step 4

   Divide the couscous among serving plates, top with the fish and serve with harissa and lemon wedges.

Harissa is a Tunisian chilli paste available from Middle Eastern and gourmet food shops and delis.