Measure the volume of couscous and soak in an equal volume of warm water for about 15 minutes or until all the water has been absorbed. Heat 4 tablespoons olive oil in a saucepan, add the onions, carrots, garlic and coriander, cover and sweat over a gentle heat until soft but not coloured. Add the tomatoes and the sliced chillies, season with salt and freshly ground pepper and cook, uncovered, for a further 10 to 15 minutes. Meanwhile, toss the sliced courgettes in 2 tablespoons of olive oil, add to the vegetable mixture and take off the heat.
Season the couscous with salt and freshly ground pepper and stir in about 4 tablespoons olive oil or 4 tablespoons melted butter, put into an ovenproof dish, cover with foil and a tight fitting lid. Put into a moderate oven, 180°C/350°F/Gas 4, for about 20 minutes or until cooked through.
Cook the peas in about 150 ml of boiling salted water or vegetable stock and add both the peas and liquid to the vegetables, add 1 tablespoon of chopped parsley, taste and correct seasoning. Taste the vegetables and add 1 tablespoon of fresh basil or oregano or coriander.