This section is from the book "Around-The-World Cook Book", by Mary Louise Barroll. Also available from Amazon: Around-the-world cook book.
Great difference in result may be obtained in cooking vegetables, according to the method employed in preparing them.
When cooking such vegetables as cabbage, sprouts, sea-kale, lettuce, spinach, cauliflower, etc., they should be "blanched," by either soaking in hot water for from 10 to 15 minutes, or scalded by a short but rapid boiling. This is in some cases for the purpose of whitening them, and in others for the purpose of making them firmer.
The best results will be obtained by combining the two methods, first soaking the vegetables in salted water for from 10 to 15 minutes, and then quickly boiling for 2 minutes in fresh water. Next drain as completely as possible, and then cook in fresh water, to which, in the case of such vegetables as spinach, etc., where it is desired to preserve the color of the greens, a pinch of soda has been added. Otherwise, as with cauliflower, etc., do not add soda.
Keep covered while cooking, as this retains the strength of the juices. Take care not to overcook, as that is liable to make the vegetables too soft, and certainly less tasteful. Strain off the water as soon as the vegetables have been cooked. Leaving them in the water makes them soggy and tasteless.
After draining, which should be done as completely as possible, a little butter, or a spoonful of cream may be added, which will moisten and make them more palatable. Then place the pot, covered, where it will keep warm until required.
The water drained off should be saved. It has often been remarked that a French family can live upon what an American family wastes; or, as some one has more aptly stated it, " the cook can throw more out of the kitchen window with a spoon, than the housekeeper can throw into the cellar with a shovel."
In France, when vegetables are boiled, the water is not thrown away, but is saved, and later used for " maigre" soups, and for stock when cooking other vegetables.