Cut the onion in half and each half into 8 wedges. Dice the aubergine and peppers into 2.5cm squares and toss the lot into a roasting tin. Drizzle with 2-3 tbsp of olive oil, season well and roast on the middle shelf of the oven for 20-25 minutes or until tender. Check them from time to time and flip over if beginning to brown too much.
Lay the salmon fillets in a baking tray skin side uppermost, make 2 slashes through the skin, brush with 1 tbsp of the olive oil then season well with the salt and pepper. Sprinkle with some sprigs of a herb and roast on top shelf of the oven for 12-15 minutes or until just cooked.
Stir the remaining olive oil into the couscous. Tip into a saucepan with the stock, bring to the boil and stir in the mustard and kidney beans, season well, then remove from the heat and leave to stand for 3 minutes.
To serve, jumble the cooked vegetables into the couscous and pile onto a serving dish, arrange the salmon fillets on top and spoon over any cooking juices. Serve hot, warm or cold with a good glass of chilled Australian Chardonnay.