Apparently water spinach (kangkung) has a parasite as it grows in water. How does one cook it safely to ensure that all the parasite eggs/cysts are no longer viable? I worry that with frying they could still be alive inside the hollow stems. Is there a specific amount of time that it must be cooked? Cleaning the chopping board and counter with just soap and water is okay?
Water spinach, like other delta-grown crops, is host to a variety of parasites that can infect humans. You should wash it in several changes of water; additionally some of my cookbooks (such as Asian Greens) recommend splitting the hollow stems to make sure they are clean on the inside. Some sources recommend soaking it in salt water as well.
After that, it makes sense to blanch or steam water spinach for a couple of reasons; it kills any remaining parasites, and when frying raw water spinach without blanching, the stems tend not to cook all the way through.