Originally Posted by ironchef
Constance, it's either "velvetting" as thymeless said, or it they added baking soda to the meat's marinade. We were discussing that in a thread awhile back.
Ironchef has it... its actually baking soda. The "velveting" is used from what i gather in chicken only. In beef, they use a pinch of baking soda in the marinade which chemically reacts with the meat giving it a tenderness, but if overdone gives it an aftertaste. I remember David Rosengarten covering this topic in his Food Network show "Taste" eons ago... he has a website, maybe you can find some info there.
EDIT: after reading the other thread on the subject, i wanted to point out that "velveting" involves the use of egg whites along w cornstarch, and the technique of the marinating with both does the tenderizing, it seemed too many posts concluded that the cornstarch alone was the tenderizer, equating the chemical interaction of the cornstarch alone with the meat to the effect the baking soda alone has with the meat.