Culinary standards are often determined by prosperity. In Japan's past, food was not always as abundant as it is now. In lean harvest years, there was no rice to import from foreign nations and no cheap vegetable stocks to rely on when the local crop failed. Polished white rice was scarce among peasants and a variety of "lesser" crops — millet, buckwheat, etc. — were cultivated to supplement their meager diets.

Lack of refrigeration was also a factor in the development of Japanese cuisine. As we have seen in the last few weeks, there are many ways to extend the life of the humble daikon — the large white radish so prevalent in Japan. This week we will look at dehydration — sun-drying or freeze-drying — as a method of lengthening the life span of this important vegetable.

Sun-drying is probably the easiest method of food preservation. Slicing something fairly thin, whether it is a vegetable or a meat protein, and laying it out to dry under the hot sun — what could be more basic? Harvest just a minuscule amount of the sun's energy, and you have extended the shelf life of a food item at least tenfold.