Dubbed "the world's hardest dish" -- literally -- a traditional stir-fry featuring stones as its key ingredient has sparked culinary curiosity on Chinese social media.

Patrons are supposed to suck on the small rocks to relish the rich and spicy flavor of the dish, which originated in the eastern Chinese province of Hubei.

They are instructed to suck off the flavors, then spit out the rocks -- hence the dish's name suodiu, meaning "suck and dispose."

Videos of internet users sampling suodiu have sprung up all over Chinese social media platforms over the past week.

They also show how street vendors cook up the unusual dish. Vendors pour chilli oil onto pebbles sizzling on a teppanyaki-style grill, sprinkle garlic sauce all over them, then stir-fry everything with a mix of garlic cloves and diced peppers.

As they prep the ingredients, these sidewalk chefs sometimes narrate their every move with rhymes, according to videos on Xiaohongshu, China's equivalent to Instagram.

"A portion of spice brings the passion alive," the chef said in one video, adding that the dish is as popular as alcohol.

Customers are then served the flavored stones in palm-sized boxes. Each portion costs about 16 yuan (US$2.30), according to the video.

"Do I have to return the pebbles to you after I finish?" one customer asked in the same clip.

"Bring them home as a souvenir," the chef quipped.

Suodiu is believed to date back hundreds of years. It was passed down for generations by boatmen through their oral history, according to a local media report.

Back in the old days, boatmen could become stranded in the middle of a river and run out of food while delivering goods.

To "find happiness in the bitterness," the report said, they would find stones to cook with other condiments to make a dish.