Did a stint at KFC cook as a teen.

The chicken fryers have a cylinder at the bottom which collects all the bits of chicken and breading that falls off as part of the cooking process. Each time the "mats" (short for Collectramatic, which is the type of fryer used) are cleaned, that cylinder is emptied. The excess oil is drained off, filtered and reused.

The solids are left to strain and solidify in the coldroom, then portioned out. When it comes time to make a batch of gravy, it is added to boiling water with gravy powder. After mixing and cooking, the solids are strained out and voila, gravy.

It is what makes the gravy thick, fatty and tasty. But the stuff that comes out of the fryers is brown, greasy and gritty, and looks the complete opposite of appetising.

The potato is powdered and comes in packets.