I think the whole point about Farfech'd is that he is a dish served with the leek he carries. I think even the anime has eluded to that being their purpose. (You certainly wouldn't battle with one, not with stats like that.)
I'd chop up the leek and sweat it in some olive oil then add it to a brine with some salt, sugar and carrots. Let the raw Farfech'd brine in that overnight then roast with the chopped up leek stuffed in its cavity while cooking.
I'd chop up the leek and sweat it in some olive oil then add it to a brine with some salt, sugar and carrots. Let the raw Farfech'd brine in that overnight then roast with the chopped up leek stuffed in its cavity while cooking.