Make your “eggs" by thoroughly whisking together the warm water and flaxseed meal. Set aside.
Whisk together sorghum flour, potato starch, tapioca starch, sugar, kosher salt, baking powder, and xanthan gum. Set aside.
Melt the chocolate chips and shortening together. Once smooth and completely melted, stir in vanilla, hot water, and the "egg" mixture. Pour this into your flour mixture, and stir just until combined. Do not use beaters.
Pour batter into a lightly greased 9x9x2 inch brownie pan, and bake for 35-45 minutes at 350 degrees, or until an inserted toothpick comes out clean. Cool completely before cutting into squares. These can be wrapped and frozen for later use.