It's a little yellow bud, and when you put it in your mouth, something strange happens.
It's a reaction that feels "a little north of Pop Rocks, and south of putting a 9-volt battery in your mouth," says Keith Dusko, director of operations for Haru, a chain of restaurants in New York, Boston and Philadelphia.
The plants are known in the U.S. as "Szechuan buttons," "sansho buttons" or "electric buttons," and chefs here have been experimenting with them for the past couple of years.
Dusko uses them in two cocktails — one is a martini-like drink with a broken-up button rimmed around the edge of the glass. Rob Welland, the executive chef at Poste in Washington, D.C., is planning to debut an Alaskan halibut dish that integrates the button into a curry sauce.
"It's not just a flavor, it's a feeling," he says, "and I thought that was interesting to introduce into the cuisine."
Michael Nestrud, a graduate of the Culinary Institute of America, says the plant, known as Acmella oleracea or para cress, has been widely used in South America, Africa and Asia.
"They actually use it as a flavoring in chewing tobacco in India," says Nestrud, who is working on his PhD in the field of sensory evaluation at Cornell.
Although the recommended serving size is only part of a button, guest host Robert Smith decided to pop a whole one into his mouth.
"Oh. It's like eating grass," Robert says. "Oh... oh... oh... There's a total tingle on the tip of my tongue... I'm producing massive amounts of saliva."
Nestrud says the compound that causes this reaction is called spilanthol. It's similar to capsaicin, the compound that gives chilies their heat. It triggers a reaction in the trigeminal nerve pathway, which is responsible for motor and sensory functions in the mouth.
The buttons aren't widely available just yet — you can buy them at some fancy grocery stores and from high-end suppliers such as Koppert Cress in New York.