In a medium bowl mix the all purpose flour, wheat flour, and sugar.
Warm the buttermilk in the microwave or on the stovetop until just lukewarm. It's okay if it looks like it's curdled. Add the buttermilk to the flour mixture, followed by the starter. Stir to combine and cover with plastic wrap for 12 hours in a warm location.
After 12 hours, preheat a waffle iron and lightly grease with your choice of oil.
Mix the egg, butter, salt, and baking soda together in a small bowl and pour into the flour and starter mixture. The batter will immediately begin to bubble and will be light and airy.
Add 1 to 1 1/2 cups of batter to the waffle maker and cook until steaming stops and your waffle is your desired color.
Serve warm with maple syrup and butter.