There are more GF mixes than you can shake a stick at and it is a very personal kinda thing cause when you can’t have the normal stuff you really want to get it as close as you can.  This is my mix that I use cup for cup for regular flour, I have had GREAT luck with it for all types of foods.

2 cups sorghum flour,  3 cups brown rice flour,  3 cups white rice flour,  2 cups tapioca flour, 2 cups potato starch,  1/2 cup ground flax seed,   /2 cup potato flour,  1/4 cup xanthan gum

Mix all together in LARGE and I do mean LARGE container and then store in fridge.

I use a small coffee grinder and I whiz instant potato flakes to make the potato flour, I also whiz -read grind the flax seed  ( I don’t care for the coarse stuff )