This fantastic recipe is from veganbaking.net. The author does an excellent job explaining why this recipe works and offers several variations. I highly recommend reading through it. Soy milk works best because it curdles the best, but you can substitute other non-dairy milk. You'll find the soy lecithin and xanthan gum in natural food stores or in some well-stocked baking sections. (Xanthan is used a lot in gluten free baking.). If all else fails, there's always amazon. The author put very precise amounts in his recipe but to make them show up correctly here, I had to put each amount on its own line -- it's not a mistake, you should add all the amounts in.