In a large bowl whisk together flour, sugar, salt, buttermilk powder and baking soda. Create a well in the middle. Set aside.
In a medium bowl combine sour cream, eggs, vanilla and vegetable oil. Stir in seltzer water.
Pour wet mixture into the well of your dry ingredients. Gently stir until combined but still lumpy.
Heat your waffle iron. Spray with non-stick spray if desired (not all waffle irons will need this). Coat heated waffle iron with batter and cook until desired crispness is reached. Serve warm.
These may be stored in the refrigerator or frozen and reheated at a later date.
Notes
*Cook time will vary with each waffle iron. Recipe source: America's Test Kitchen