This is one of the most popular home-cooked Lebanese family meals. Ideally choose those pretty pale green, squat, bulbous zucchini stocked by European and Middle Eastern greengrocers in summer, as they are easy to hollow out. Baby marrows work well too. Regular, long zucchini require a little more patience and a long thin knife (like a fish filleting knife) to scrape out the insides, while maintaining the whole long shape of the vegetable. Koussa makes a simple supper dish, served with thick creamy yoghurt.