Place all-purpose flour, whole-wheat flour, milk, water, flaxseed meal, salt and sugar in a blender; blend until smooth. Refrigerate until slightly thickened, 10 to 20 minutes.Advertisement
Dab a piece of crumpled paper towel with oil and rub it over the surface of a 10-inch nonstick skillet. Heat over medium heat. Add 1/4 cup batter, swirling to coat the bottom. Cook until edges are dry and the bottom is lightly browned, 2 to 3 minutes. Flip and cook until the bottom is lightly browned and the edges are dry, 2 to 3 minutes. Reduce heat, if necessary. Slide the crepe onto a plate. Repeat with the remaining batter, rubbing the pan with oil as needed.
To make ahead: Stack the crepes, placing a piece of wax paper between each one, wrap and refrigerate for up to 2 days or freeze for up to 1 month.