Não é necessário capturar um fochon gras torchon. Essencialmente, o fígado é uma charcutaria curada antes que a etapa de caça ilegal ocorra. A partir deste Serious Eats método de preparação:
To Cook or Not To Cook?
At this stage, the most classical of recipes will have you poach your torchon in a bath of sub-simmering hot water for about 20 minutes, long enough to bring the whole thing into the range of 130 to 140°F, effectively cooking it. More modern recipes, such as Thomas Keller's go for a much, much shorter cooking time—about 90 seconds. Tasted side by side, I've always preferred the shorter cooking time. The foie is denser, has a more buttery texture, and doesn't leak as much fat when you slice it or eat it.
I always wondered why this was until I came to what was a pretty obvious realization: Thomas Keller's 90-second poached torchon is essentially uncooked. I stuck a thermometer into a torchon during its simmer and measured the internal temperature. It started at around 40°F, and finished exactly where it started. Aside from the outer few millimeters, absolutely no cooking occurs in a 90-second poached foie. No wonder the texture is so significantly different—we're essentially eating raw cured liver here!
There is, however, a good reason to poach the foie, even if it's only for a brief period: The exterior layers soften enough that you can wrap the cheesecloth even tighter, giving you a better looking finished product. That Thomas Keller poach is really all about appearances!
Para quem não conhece, este artigo de D'Artagnan explica as diferenças entre foie gras terrine e foie gras torchon. (Sem endosso pretendido, apenas boa informação.)