Mix the flour, cornmeal, baking powder, baking soda, salt, and lemon zest. Set aside.
Separate the eggs carefully and set the yolks aside.
Whip the egg whites with the cream of tartar until they hold stiff peaks. Set aside.
Beat the egg yolks with the buttermilk and butter until well mixed.
Add the yolk mixture all at once to the cornmeal mixture and mix quickly - just until batter is smooth.
Fold in half the beaten egg whites to loosen the mixture up.
Carefully fold in the remaining egg whites.
Pour about ¾ cup of the batter onto the hot waffle iron and bake according to manufacturers instructions. The exact amount you need will depend on the actual waffle maker you use.
Notes
yellow cornmeal may be substituted for the blue cornmeal.