The Dangerous Soup, was served in the episode, "The Tale of the Dangerous Soup".
During the events of the episode, Dr. Vink had opened a fancy and successful new restaurant called "The Wild Boar". It was right here then, where Dr. Vink has established himself as a gourmet cook. His specialty and most successful dish was "La soupe dangereuse" better known as "The Dangerous Soup".
This soup was simply delicious and irresistible, word of it got out and many people had traveled from far away to try a bowl of it. The soup costed $100 a bowl and each customer was only limited to one bowl each. Dr. Vink begun to make a vast fortune with this soup.
What all of the customer didn't know, was the mysterious secret to this soup's recipe. What looked to be just plain Green Pea or Zucchini Soup, really had a dark and evil secret!
The secret ingredient was, an elixir of the actual emotion of fear. Since fear is a powerful emotion, it also has a powerful taste. Dr. Vink extracted fear out of his restaurant employees, by locking them inside a chamber and exposing them to a Gargoyle. This Gargoyle would look right into their minds, and create illusions of their greatest fear. The weaker their will was, the more scary the illusions were. Therefore this would help produce more of the elixir.
Dr. Vink was very stern and serious about his customers and employees only having one bowl and one free sample each. He would fire them from their jobs, if he caught them having anymore. It is unknown, if Dr. Vink still continued to make and sell this soup after the events of the story ended.