In a medium bowl place the bean flour, cornstarch, tapioca flour, and salt. Whisk together
Add the egg and beat together until smooth. Slowly beat in the water. Let rest in refrigerator for at least 20 minutes
Heat 9" skillet or frying pan over high heat, brushing the pan lightly with oil. Be sure it is hot enough for water to dance on before starting to cook the tortillas
Spoon in about 4 tablespoons of batter or enough to just cover the bottom of the skillet
Cook until the bottom of the tortilla is golden brown and the edges curl up and the top seems dry
Turn and barely cook the other side. Slip onto wax paper. Repeat
Store separated by wax paper in a plastic bag in the refrigerator or freezer until ready for use
