Seitan (Japanese), also called, Wheat gluten, wheat meat, gluten meat, or simply gluten, is a food made from gluten, the main protein of wheat. It is made by washing wheat flour dough with water until all the starch granules have been removed, leaving the sticky insoluble gluten as an elastic mass which is then cooked before being eaten. Seitan is sometimes called mock duck but there's no real duck or real meat in it.
Wheat gluten is an alternative to soybean-based foods such as tofu, which are sometimes used as meat substitutes. Some types of wheat gluten have a chewy or stringy texture that resembles meat more than other substitutes. Wheat gluten is often used instead of meat Asian, vegetarian, Buddhist, and macrobiotic cuisines. Mock duck is a common use for wheat gluten.
Wheat gluten first appeared during the 6th century as an ingredient for Chinese noodles. It has historically been popular in the cuisines of China, Japan and other East and Southeast Asian nations. In Asia, it is commonly found on the menus of restaurants catering primarily to Buddhist customers who do not eat meat.
Adapted from Wikipedia