What makes egg drop soup so popular? in China: Cooking & Baking Posted November 8, 2007 When my family ran restaurants we never thickened the "egg drop soup" with cornstarch or anything else. It was good old back burner stock, seasoned and "thickened " with beaten egg whites. Ours was different in that we called it "mushroom egg drop soup" because we added some sliced mushrooms and a few bits of scallion.In Chinese, we called the soup dan fah tong, or egg flower soup.I have not encountered the soup by either appellation in my travels outside of North America. But, that's not to say that it does not exist in some other guise.