Pour a sufficient amount of oil into the pan and put the potatoes in a solid layer, slightly overlapping each other. Season with salt, pepper and sprinkle with nutmeg. Put on a slow fire and cover. Cook for 20 minutes. Potato slices should be soft.
Add salt and pepper to the onion and mushrooms, fry until half cooked.
Bake potatoes, onions and mushrooms under the grill until cooked.
