Cooking oilColleen Christensen has asked:

Is there anything one can do with rancid cooking oil?

(I don’t know how rancid she means by rancid but let’s assume she just means used and therefore slightly icky - say oil or lard from deep frying - rather than full on bleugh.)

I know that commercial fryers can recycle their old oil (for use as biodiesel) but what about domestic chefs who aren’t using anywhere near as much? And what about other uses?

(Photo by float)