Serge from BabkaThis video on "Ethical Fois Gras" mentions that the technique used is a Sephardi technique[1]. It doesn't go into detail about how geese products can be used to produce kosher versions of other food, such as ham, and even kosher prosciutto which was made by Jews in Italy.
https://www.youtube.com/watch?v=e_vWB5bdbeE
1. Though not expressed in the best way