Even with foods of good quality, much of their value may be lost or wasted through improper preparation. We have already mentioned that vegetables should be baked, steamed, or prepared in a pressure cooker, in their own juices, with little or no water added, since the ordinary way of cooking wastes or destroys many of the valuable elements.
If you have no steaming utensil or pressure cooker available, the ordinary cooking utensils will do. In this case, however, add only a little water to the vegetables and steam them over a low flame.
Cooking utensils should always be covered tightly to prevent the escape of valuable ingredients.