Combine almond flour, coconut flour, xanthan gum, baking powder, and salt in the bowl of a food processor; pulse until well combined. Pour apple cider vinegar into the mixture and blend until smooth. Add egg and water, 1 tablespoon at a time, and blend until a sticky dough ball is formed. Place the dough on a surface sprinkled with almond flour and knead until soft, about 2 minutes. Wrap dough in plastic wrap and let it stand for 10 minutes. Divide dough into 8 equal balls; roll out each ball into a 5-inch disc between two sheets of parchment paper.
Heat an iron skillet over medium-high heat and grease with cooking spray. Place dough disc in the hot skillet for just 5 seconds; flip it immediately with a spatula, and cook until lightly golden, about 40 seconds. Flip and cook for another 40 seconds.