In a large bowl combine the flour, sugar, milk, and sourdough starter and mix well.
Cover the bowl with plastic wrap and let sit on the counter overnight or for 8-10 hours.
In a medium bowl whisk together the eggs, butter, cinnamon, salt, and baking soda.
Add the egg mixture to the flour mixture and whisk until mostly smooth.
Preheat the oven to 200 degrees. Place a baking sheet in the oven.
Spray a waffle iron with cooking spray.
Measure 2/3 cup of batter and pour it into the waffle iron. Cook according to the manufacturers instructions.
Place the cooked waffles on the baking sheet in the oven.
Serve with whipped cream and fresh berries if desired.