Bitter gourd, which we often eat in our life, is called cold melon in some places. It came from abroad. It was first spread from the western regions in the Tang and Song Dynasties and from today's Arab region. Bitter gourd should be golden brown when it is ripe, and there are things that look like beans in it. It's not bitter. Arabs use it to stew soup and cook, but the skin is discarded. After it was introduced into China, people found that it was not mature. When it is still green, it is difficult to cook.