In a conventional potato cake, egg is often doing that work. In a vegan recipe, though, you're not going to use egg. And there are three things that help bind these potato cakes together. 1. Potato starch is a natural binder, and when you mash a potato, you release some of that starch. 2. The second binder you're using here is flaxmeal. Normally, when you make a flax egg, you want to whisk the flax meal with water and let it sit to thicken. In this recipe, though, you can just mix the flax right into the batter, because the flax will soak up moisture from the batter as you blend it together. 3. Chickpea flour is also a great binder. It can go by other names: garbanzo bean flour, besan, or gram flour. Graham flour is not the same thing as gram flour, so it will not work in this recipe. Please do not substitute other flours in place of the chickpea flour, because your potato cakes will end up too soft. *One important note: You must use flax meal. Do NOT use whole flax seeds for this recipe. Flax seeds do not soak up moisture, and they will not give you the binding power you need. I don't want your potato cakes to fall apart on you!