Joe puts his foot down.

Reader Leonard M. writes in with a question about frying oil:

Dear Joe,

I read your posts on oil freshness will great interest, since it seems every recipe I have for deep fried food calls for 100% fresh oil. Many of them in fact instruct that old oil and new should never be mixed. I just want to be clear: are you telling me that all of that is wrong?

Yes Leonard, at the risk of sounding dictatorial, I am. In fact I will go so far as to say no food should ever be fried in all-new oil. I rarely get emphatic like this, but take it from a guy who’s done a lot of frying in his life: fry oil should always be at least a little bit “soapy”.