Heat the waffle iron according to manufacturer's instructions.
Whisk the flours, cornmeal, salt, and baking soda together in a large bowl.
In a separate bowl, whisk the egg yolks and melted butter together, then whisk in the buttermilk and maple syrup until uniform.
In a large bowl, whip the egg whites and cream of tartar with an electric mixer on med-low speed until foamy, about 1 minute.
Increase the speed to med-high and whip the whites to stiff peaks, 3-7 minutes.
Make a well in the center of the dry ingredients, pour the buttermilk mixture into the well, and whisk very gently until the buttermilk mixture is just incorporated (a few lumps should remain).
Toward the end of mixing, fold the whipped egg whites into the batter with a rubber spatula.
Spray the hot waffle iron with vegetable oil spray, then spread the appropriate amount of batter onto the waffle iron, following the manufacturer's instructions, and cook until golden brown, about 3 1/2 minutes.
Remove the waffles from the waffle iron and serve,.
Repeat with the remaining batter, spraying the waffle iron with vegetable oil spray as needed between batches.
Per serving (1/2 cup batter)--300 calories, 10.5 g fat, 42 g carb, 10 g protein 3 g fiber.