Preheat the waffle iron to a medium high heat according to the iron instructions--for my iron, I preheated to 5 out of 7.

Place the eggs in the bowl of a stand mixer (you can do this with a hand mixer or rotary beater, it will just be more of a pain). With the whip attachment, begin beating them on medium low speed, gradually increasing the speed until it is on high. Then leave the eggs to beat for 3 minutes.

While the eggs are whipping, measure out the white whole wheat flour by placing the tablespoon of potato flour into a 3/4 cup measuring cup, and then filling the cup the rest of the way with white whole wheat flour. Whisk together the flours, including the potato flour, the baking powder and salt. Set aside.

When the eggs are pale and thick, add the sour cream and milk, and return the mixture to beating on medium high for another 2 minutes. Beat in the sugar.

Remove the whip attachment, and with a spatula, gently stir the flour mixture into the egg mixture. Fold in the melted butter.

Ladle 1/4 cup of batter into each waffle well (this is for a 4 square Belgian waffle iron--obviously if your iron takes more or less batter, adjust accordingly). Cook until the waffle is golden brown--you know your waffle iron best, I usually do not check mine until it has returned to temperature.

Serve immediately with salted butter and maple syrup.

These waffles also keep well for a day or 2, in an airtight container in the fridge. Reheat carefully (i.e., do not burn) in a toaster.