Dirt: It's what's for dinner

(CBS News) Animals and even humans have been known to munch on dirt and clay as it's said to provide digestive and other health benefits, but among the ranks of trained chefs, dirt has never been taken seriously, until now.

At some restaurants in downtown Tokyo, the food is dirt, literally. The rich black soil normally used to pot plants go into the pot in some kitchens.

Chef Toshio Tanabe, who runs an elegant French-style restaurant in Tokyo, said "dirt goes great with just about anything, but especially root vegetables, like carrots, potatoes and radishes. It complements oysters too."

These gritty treats don't come cheap, either. The six-course earthy feast will set you back more than $100.

Kazue Nagatsuka, a diner at Tanabe's restaurant, said the first course, a murky mud-and-spud soup, was hard to believe that "it's really dirt" and that "it seems really healthy."

Tanabe's latest filthy recipe is mashed potato and ruccola greens with a generous drizzle of scary-looking mud sauce.

"Trying a new flavor, encountering a different taste, I believe, is part of the joy of eating," Tanabe said.

Tanabe has many fans with his mud-based cuisine, but for all but the most intrepid foodies, this menu may be a bit too down-to-earth.