Lookit, Asian people eat all kinds of plants and animals for that matter. It's hard to keep up. A Hmong farmer a while back said to me that you can eat practically everything. "There's no harm in trying," he said. The Hmong are fearless survivalists. They are people who eat fresh Sichuan peppercorns that numb your mouth and leave a biting spicy bitter taste on the palate for about 30 minutes.
I thought of them because two people have recently asked about the same oddball vegetable lately. Elise in Massachusetts queried and then sen in the photo of what she recently bought at a Viet market in the town of Lowell. They were labeled "bass leaves."
In New York a few weeks ago, I saw packages of vines and leaves resembling Elise's bass leaves. They weren't labeled as bass leaves. My friend James Oseland, a fellow Southeast Asian food expert and editor in chief of Saveur magazine, was with me and said that they were morning glory leaves. We later got some takeout Thai food from a video store in Flushing and the leaves were in a stew/curry of sorts. I can't remember whether or not there were stems and tendrils. Overall, the vegetable didn't taste like much, nor did they impart interesting texture. On the other hand, the food was extremely spicy and could have easily overwhelmed any flavor the vegetable had.
A few days ago, Jaden of the Steamy Kitchen blog in Florida asked about an unfamiliar, kinky Asian vegetable. She sent me one of her handsome photos of a seared scallop dish thay she prepared and set atop the vegetable in question. At first I thought the kinky veggie was curled up water spinach stems (rau muong) but she had some large, heart shaped leaves in the bowl.
So what do you folks on the East Coast have? I do think that it's morning glory vine and leaves, as James identified. Morning glory belongs to the huge Ipomoea family comprising of 500 different species. They grow very very quickly and have pretty trumpet-shaped flowers. Most gardeners think of them as weedy pests and like to grow them in containers to control the vines. But Ipomoea plants aren't ornamental. In fact, sweet potatoes are members of that genus.
Guess who grows lots of sweet potatoes (Ipomoea batatas) ? Southeast Asian farmers. Typically what we see at Asian markets as "yam leaf" are non-producing sweet potato vines (see photo below). They have delicate hear-shape leaves and you stir-fry just the leaves and discard the stems. They have an earthy flavor and are slightly slimy when cooked but not offending gross.
Those same farmers usually cultivate sweet potatoes too, and now is the season to harvest the potatoes for market. I suspect that they're bringing the vines too as a way to maximize their earnings. I've not seen these leaves on the West Coast but will keep an eye out. Above is a photo of a type of sweet potato plant. Below that is a typical morning glory flower.
If I were to get a hold of some, I'd try stir-frying or blanching the leaves and stems separately and see if they're flavorful.
If you're familiar with this vegetable, do share your thoughts!
11/28/07 Update: Turns out I was wrong. "Bass leaves" aren't morning glory vines. Read the comment thread to find out what they really are!