I'm surprised no one has asked me what's in the mason jar. When I first started living with my wife, she was all freaked out about it.
I thought it was cornstarch and water and now I am curious.
It does kind of look like cornstarch and water, but it isn't, it's rendered pork fat, which I almost exclusively cook with. When I first started living with my wife twenty years ago, she was completely aghast at the various rendered oils that I started keeping in the refrigerator. At any given time, there would be bacon fat, rendered leaf lard, rendered pancetta and rendered salt pork, plus a jar of achiotina (lard with annato seeds) for latino dishes.
My wife has never been big on meat items, especially pork products, but with time, I've taught her the wonders of swine. She now asks me to make dishes with Italian sausage, Spanish chorizo and Portuguese linguica & chourico. I'm not a religious person, in fact I'm an atheist, but if there is a God, then I thank him for creating the pig.