Light the barbecue, setting the boiler temperature to 180 °C. Cook the pearl couscous in the vegetable stock until it is tender. Cut the spring onion into thin rings and crumble the feta cheese. Season the couscous with the olive tapenade, pomodori marinati, spring onion, garlic, feta cheese and aio e lemone. Add a little salt and pepper if necessary. Cut the top off the sweet peppers and scoop out the centres, then brush them lightly with oil. Fill the sweet peppers with the couscous and place the tops back on them. Cook the sweet peppers for about 45 minutes on the barbecue.