This article is from the Vegetarianism FAQ, by email@example.com (Michael Traub) with numerous contributions by others.
Seitan is a form of wheat gluten. It is a high protein, low fat,
no cholesterol (of course) food that is usually found in the
refrigerated section of most organic groceries/health food stores.
It is usually near the tofu and typically comes in small tubs
(like margarine tubs). It is brown and sometimes comes in strips
1/4 to 1/2 inches thick. Seitan is made from whole wheat flour
which is mixed with water and kneaded. This dough undergoes a
simple process of rinsing and mixing to remove the starch and some
bran until a gluten is obtained. After boiling in water, this
glutenous dough is called Kofu, which can be further processed in
many ways. One of which is seitan. Kofu becomes seitan by
simmering in a stock of tamari soy sauce, water and kombu sea
vegetable. Seitan can be used in sandwiches, or to make dishes
such as sweet and sour seitan, seitan stir fry, salisbury seitan,