Wash the spinach thoroughly. Place the spinach and half the salt in a saucepan. Cook over a high heat for 1 minute, stirring constantly. Reduce the heat to moderate and cook for 5 more minutes. Remove the spinach from the pan and drain. Place spinach on a board and chop coarsely. Heat butter in a large sauce pan. Add the onions, ginger, chilies, and fry, stirring, until the onions are golden. Stir in the turmeric and add the potatoes. Reduce the heat to low, cover the pan, and cook until the potatoes are tender. Add the spinach, increase the heat to moderate, and cook for 5 minutes or until all the excess moisture has evaporated. Serve hot.{$7e}(Original recipe for 4)