What is the origin of this saying?
The original phrase is “The proof of the pudding is in the eating” and was generally used to say that one had to taste one’s food in order to know if it was good.
Actually at the time the saying originated, pudding was not the dessert we know now. Instead it was a meat item resembling a sausage. Back in those days, meat items were easily contaminated and the only to way determine such a thing was to take a bite out of it.