Bring a saucepan of lightly salted water to a boil, add the potatoes, reduce the water to a simmer, and cook the potatoes for about 12 minutes until tender. Drain, allow to cool and then slice.

Heat the oil in an ovenproof non-stick medium frying pan. Add the onion and sauté for 2 minutes. Then add the zucchini and sauté for another 6 minutes (4 minutes if using grated zucchini). When the zucchini is cooked, add the tomatoes and cook for 2 minutes, then stir in the sliced potatoes.

Beat the eggs together with the milk, Parmesan and a little seasoning. Pour the egg mixture over the vegetables and cook over medium heat for about 4 minutes until the underside of the eggs has set. Meanwhile, preheat the broiler to high. Place the frying pan under the broiler with the oven door open and the handles sticking out and cook for about 3 minutes until golden and set. Slice the omelet out onto a plate. When the omelet is cold, cut into wedges and wrap in foil.

Makes 6 portions.