Soy is pretty easy to sub for. About the only thing they could use that is irreplaceable is tofu. I use Vegan Cupcakes Take Over the World, and replace all the soy milk with hemp milk, all the soy yogurt with coconut milk yogurt, and all the wheat with bob's red mill ap gf flour and xanthan gum. They come out great! I'm definitely interested in giving this book a looking at!