Siamese Watercress with Yellow Beans and Garlic

THIS STIR-FRY IS a favourite of the Thais. Often they crumble a little roasted kapi (shrimp paste) and a few dried prawns (shrimp) into this dish. In the provincial capital of Phitsanulok, there are several riverside food stalls, one of which has become famous for the manner in which it serves its watercress. After cooking the watercress in a wok, the cook runs across the road and flings the vegetable at the hapless customer, who attempts to catch it on his or her plate — sometimes not so s