I hope you are not going to be too offended if I say I am not a biggest fan of yam. I love pounded yam, but boiled yam is kind of too dry to my liking. That is why I prefer to use potatoes if I want to make porridge.
And because I like sweet potatoes and they look very much like yam (I mean, on the surface), of course the idea of using sweet potato for porridge came in my mind. Try my recipe if you can buy sweet potatoes in place you live and tell me what you think about it.
Learn more about ingredients in this recipe: Ground Dried Crayfish