They are usually harvested immature, when they are anywhere from 30 to 45 cm (12 to 18 inches) long, so that they can be eaten as “fresh” beans, the way green beans and runner beans are.
Long Beans are very closely related to the bean plant that produces black-eyed peas. If left unpicked, the long bean pods will grow up to 1 metre (3 feet) and produce inside beans that look very similar to black-eyed peas. For this reason, some people think mistakenly that it is the same plant (it’s not: the black-eyed pea bean is Vigna unguiculata ssp. dekindtiana.)
There is a “white” variety which is actually light green, a more common variety that is dark green, and a purple variety. The purple ones are similar in taste and texture to the light green ones. Depending on the variety, the seeds inside can be black, white or purplish.
Long Beans have a taste similar to standard Green (string) beans, though if anything the lighter ones are slightly sweeter. The dark green ones have more of a grassy taste. Fresh long beans are less crisp than green beans, as have they less water in them, but on the upside, that means they won’t add liquid to a dish when you don’t want it. There is never any stringy spine that needs removing.
Outside of Asia, Chinese Long Beans are being grown in California, The Dominican Republic and Mexico.
When buying, choose long ones with smooth skins and no swelling of the seeds inside (though in China, they often prefer them that way.)
Wash, shake dry, top and tail, then chop into small pieces for cooking (or just snap into pieces). Cook as you would green or runner beans, or use in a stir-fry. Don’t overcook or they won’t just soften, they will go mooshy. Allow around 1/4 pound (110g) per person.
In Asia, they will also steam the leaves and stems.
French fillet beans, Green beans, Runner beans (though these beans will give off more moisture than Long Beans will).
Long Beans dry out quickly. Store unwashed in a plastic bag and use within a few days or a week max.
Native to South Asia.
In Thailand, called “tua paak yao” (also spelt “tua fuk yao” in English.)