Check out this HowStuffWorks podcast to learn more about the mysterious ingredients of hot dogs.

That quest sometimes prompts the use of mysterious ingredients of no known biological value.

Taking a break from campaigning the other day, Mr. Bradley remarked that the way voters make up their minds is the "mysterious ingredient in our democracy."

"The other drinks have mysterious ingredients."

Bargaining power, whether belonging to an individual or a group, is sometimes regarded as a rather mysterious ingredient and indeed there is a multitude of definitions.

And which mysterious ingredients were suspected carcinogens?

The medical profession continued to criticize the method and many tried to identify the mysterious ingredients.

Apparently I still lacked some mysterious ingredient with which to bring all the skills together into a harmonious, effective whole.

The mysterious ingredient: great good, utterly contemporary young-teen-age humor.

"What's so fascinating is to see how often the ups and downs of history derive from that mysterious ingredient called personality," he says.