I forgot something in my previous post that is important. Potato starch is acceptable for a gluten free diet, but not a good choice for a CKF diet. People on a CKF diet can have potatoes, but the potatoes have to be specially treated. It isn't difficult to do, it's just time consuming. Two of my FIL's favorite foods were mashed potatoes and potato salad, and he could have both occasionally but we had to treat the potatoes first.
You can not use instant mashed potatoes. You have to use regular potatoes. You peel them, cut them, and then soak them in water for an hour or two. Drain the water that you soaked the potatoes in. This process leaches out a fair amount of the potassium that is in the potatoes. Then boil your potatoes and again drain the water off. This leaches out more of the potassium. Once done this way, turn them into potato salad or mashed potatoes. Use non-dairy creamer and margarine in the mashed potatoes or to make them special, blend in some softned cream cheese. Also, if you're doing a pot roast, the potatoes in the pot roast have to be treated the same way.
Another acceptable pie crust can be made with corn chex or rice chex. Crush them like you would to make a graham cracker crust.