1. Weigh or lightly spoon flour, potato starch, cornstarch, and flaxseed meal into dry measuring cups; level with a knife. Combine flour, potato starch, cornstarch, flaxseed meal, brown sugar, and next 5 ingredients; beat with a mixer at low speed until blended. Add oil and egg white; beat until mixture is coarse and crumbly. Slowly add 1/2 cup hot water until dough pulls away from sides of bowl, beating constantly.
2. Turn dough out onto a well-floured surface; divide dough into 8 equal portions, shaping each into a ball. Place on a large plate; cover with a damp cloth and refrigerate 10 minutes.
3. Roll each dough ball into a 10-inch circle on a well-floured surface. Place a 9-inch plate upside down on top of each circle. Cut away excess dough on each using tip of a knife.
4. Heat a large skillet over medium heat. Coat pan with cooking spray. Cook each circle 20 to 25 seconds or until it begins to bubble. Turn circle over, and cook 20 to 25 seconds. Cool completely. Store in an airtight container.