You've covered dairy and acid ingredients, but I honestly have no idea what "Unrendered Berkshire pork fat" is or where I would get it. Is that bacon grease? Saltpork? Lard is common but rendered.

Thanks! It's entire chunks of fat from a Berkshire pig. Lard works too and is what you get when you render pork fat, but the rendering removes some flavor. I'll update the recipe.

Probably suet, which is raw and found around kidneys and loins.