The technique is relatively simple in and of itself. Using the high speed techniques of the school, it the user forces others to eat their food for them, so quickly and discretely that the other diner isn't even aware that their opponent is feeding them. The move was named after the method of making fois gras in which a goose is forcibly fed without cease in order to fatten its liver, and it takes advantage of two core rules of the Martial Arts Dining style. Firstly, the aim is to eat so quickly that nobody, not even an official judge, can see you eat. So there is no way to prove that the practitioner using Parlay du Fois Gras isn't eating the food themselves. Secondly, there is no official ruling that a participant has to actually eat the food themselves. Thusly, even if the user of Parlay du Fois Gras is seen using the move, it is their opponent who will be penalized, at least in a fair match.
This technique was developed by a practicioner of the school aptly named "Le Petite Bouche" or "the little mouth", who used the technique rather than train his mouth to open to grotesque proportions.
The technique is forbidden for two reasons. The first is that it is considered an affront to the school, who are proud of their wide mouths and revolting techniques. The second is far more dangerous. Since the user of the technique is feeding others rather than themselves, that means they also run the risk of starving themselves to death if they are continuously forced to rely upon it.
A counter, "The Shield du Fois Gras" was developed, where the wide-mouthed opponent of the parley user puts a plate in their mouth to prevent any food from entering. The opponent can also avoid the technique by putting their face directly into their food, but this goes against the etiquette of the school.
There is however a good thing about the Fois Gras, one can also uses it to feed him/herself but only if no one can see them eat.