Tip the sun dried tomatoes into a heatproof bowl. Pour over 500ml boiling water, and set aside for 15 mins to soak.
Tip the couscous into a separate, large heatproof bowl. Sprinkle in a pinch of salt. Pour in 300ml boiling water. Swirl with a fork. Cover the bowl with a large plate and set aside for 15 mins to soak.
Meanwhile, halve the red pepper and scoop out the seeds and white membrane. Thinly slice the flesh. Slice the cherry tomatoes in half.
Peel the garlic clove and grate into a food processor. Add the olives and 1 tsp dried oregano. Drain the sun dried tomatoes (reserving the soaking liquid). Add the sun dried tomatoes and 4 tbsp of the reserved liquid to the processor. Grate in the zest from the lemon. Pour in 1 tbsp olive oil. Blend everything into a fine paste. No food processor? Chop the ingredients together as finely as possible then stir in the oil and water.
Pour 1 tbsp olive oil into a large frying pan and warm to a medium-high heat. Slide in the sliced peppers and tomatoes. Sprinkle over a little salt and pepper. Fry for 4–5 mins, till slightly softened and glossy.
Fluff up the couscous with a fork. Fold in the cooked pepper and tomatoes, along with the rocket leaves. Squeeze in the juice from the lemon and glug in 1 tbsp oil. Stir and have a taste of the couscous. Add more salt and pepper if it needs it.
Preheat your grill to high. Pop the whiting fillets in a roasting tin. Spoon over half the tapenade and rub into both sides of the fish. Slide under the grill. Cook for 5–6 mins, till the fish is cooked through and flakes easily when pressed with a fork.
Spoon piles of couscous onto a couple of plates and top with the grilled whiting. Serve with the remaining tapenade on the side.