If you plan ahead, Hudson Valley sells Grade C Foie. Call, it's not listed on the website.
If you pan seer, no need for Grade A or removing veins.
When your Foie arrives, you have two options, freeze in it's cryovac packaging until usage or you can slice and freeze the slices for usage within a month or two.
I do not make a cooked Pate any more preferring to take a whole Foie wrap into a torchon with food grade cheesecloth and cure in a Kosher salt.-Richard
BTW, the Owner of Hudson Valley has a very nice book with excellent methods and recipes of how to work with Foie. I found my copy on eBay.