2.In a frying pan, heat oil on high. Sauté onion, zucchini and garlic for 1-2 minutes. Add tomatoes, water and 2 teaspoons oregano. Mix well, then season to taste.
3.In a large bowl, combine cheeses, breadcrumbs, remaining oregano, egg and nutmeg. Shape tablespoons of mixture into balls. Pour vegetable mixture into a large oven-proof dish. Place balls into dish.
4.Bake, covered with foil, for 20 minutes, then uncover and cook for a further 5-10 minutes.