This simple, but very flavorful soup is yet another example of the influence of Chinese foods on the cuisine of Thailand. This version of Tom Jab Chai is made by boiling pork leg bone in a rich broth seasoned with garlic, coriander root, and black pepper. To the soup we add the large white winter radish known as Daikon, some straw mushrooms, flavorful dark green pak choy (Chinese cabbage) and pak boong (river morning glory). In Isaan, soups of this type are often eaten with sticky rice, with the broth serving as a sort of dipping sauce for the rice, but we generally serve it here with a small plate of steamed Jasmine rice. The soup is spooned over the rice and eaten. However, this soup is so thick and hearty that you really won't need eat it with anything but a spoon.