It is not fair to lump these two cuisines together, but their sauces share an approach and many ingredients. The heart and soul of both cuisines is fish sauce, made by letting small anchovy-like fish ferment in the sun and then draining off the juices, which become the sauce. While fish sauce isn’t very appetizing-sounding or appealing on its own, it is what gives the best Southeast Asian cuisines their savor. It is to Southeast Asia what broth and meat glazes are to France.