Pat the prawns dry between several layers of kitchen paper.
Place the onion, chilli, garlic, fennel seeds, paprika and oil in a shallow casserole and mix well. Cover and cook in a preheated oven, 180°C (350°F), Gas Mark 4, for 20 minutes until the onions are soft.
Add the prawns and return the casserole to the oven, uncovered, for a further 15 minutes or until the prawns have turned pink.
Meanwhile, place the couscous in a heatproof bowl and add the hot stock. Leave to stand for 5 minutes until the stock has been absorbed.
Fluff the couscous up with a fork and add to the casserole with the coriander, artichokes and peaches or nectarines. Mix well and season to taste with salt and pepper. Re-cover and return to the oven for a final 5 minutes to heat through.